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555-605 Level|   Meaning/Logical Predication|   Parallelism|   Pronouns|   Subject Verb Agreement|                           
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Scientists have recently found evidence that black holes—regions of sp 01 Jun 2018, 19:46
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Verbal Question of The Day: Day 260: Sentence Correction


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Scientists have recently found evidence that black holes—regions of space in which matter is so concentrated and the pull of gravity so powerful that nothing, not even light, can emerge from them—probably exist at the core of nearly all galaxies and the mass of each black hole is proportional to its host galaxy.

(A) exist at the core of nearly all galaxies and the mass of each black hole is proportional to

(B) exist at the core of nearly all galaxies and that the mass of each black hole is proportional to that of

(C) exist at the core of nearly all galaxies, and that the mass of each black hole is proportional to

(D) exists at the core of nearly all galaxies, and that the mass of each black hole is proportional to that of

(E) exists at the core of nearly all galaxies and the mass of each black hole is proportional to that of

Every question of the day will be followed by an expert reply by GMATNinja in 12-15 hours. Stay tuned! Post your answers and explanations to earn kudos.


GMATNinja what function does dash sign have in this senntence ?

Scientists have recently found evidence that black holes—regions of space in which matter is so concentrated and the pull of gravity so powerful that nothing, not even light, can emerge from them—probably exist at the core of nearly all galaxies and the mass of each black hole is proportional to its host galaxy.

i chose actually D ....i thought "nothing" refers to 'exists"

you can answer this question on the weekend :) when you are in better mood :)
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I know that this doesn't really answer your question (and somebody else already answered it, anyway)... but here's a video about punctuation on GMAT SC: https://www.youtube.com/watch?v=JLAJ_drP8UM.

The punchline is basically that there's no real reason to worry much about the exact rules surrounding dashes, partly because English-language editors (I used to be one!) and style experts don't remotely agree on the best ways to use dashes. If you pick up a bunch of the world's best publications written in English, you'll see a whole bunch of different opinions about how to use dashes correctly -- and about whether they should be used at all. Some editors hate them.

And on the GMAT? You'll see dashes, but they're never really the deciding factor, partly because I don't think that the GMAT wants to try to settle a broader debate about dashes. On official questions, there are always more important issues in the sentence, and you can always answer the question without really worrying about whether a dash was the best choice of punctuation.

I hope this helps!
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Scientists have recently found evidence that black holes—regions of sp 21 Aug 2018, 03:01
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The sentence says that scientists have recently found evidence for two things.

The black holes probably exist at the core of nearly all galaxies
The mass of each black hole is proportional to its host galaxy
Please note that the sentence also provides a lot of information about black holes within two dashes. You can read the idea between the dashes. However, the more important thing is that when you start reading after the closing dash, read as if the dashes and everything contained within the dashes weren’t there. In other words, you shouldn’t get lost in the deluge of information in the dashes and should be able to connect the part of the sentence that appears after the dashes to the part before the dashes.

There are two problems with this sentence:

“That” is missing after ‘and’. To make it clear that the evidence suggests “that the mass of each…”, we need to place ‘that’ before “the mass of each…”. Without ‘that’, it may seem like another independent clause having nothing to do with evidence.
The second problem is with the meaning. It doesn’t make sense to say that the mass of X is proportional to a galaxy. Probably, we mean to say that the mass of X is proportional to the mass of a galaxy. Therefore, the second part of the sentence should be modified to say “proportional to the mass of its host galaxy”. Please note that when we are evaluating the options, we need to be flexible i.e. even though it seems to be “proportional to the mass of its host galaxy”, it may eventually turn out to be “proportional to the size of its host galaxy”.
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Scientists have recently found evidence that black holes—regions of sp 07 Dec 2018, 12:36
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Scientists have recently found evidence that black holes—regions of space in which matter is so concentrated and the pull of gravity so powerful that nothing, not even light, can emerge from them—probably exist at the core of nearly all galaxies and the mass of each black hole is proportional to its host galaxy.


(A) exist at the core of nearly all galaxies and the mass of each black hole is proportional to

(B) exist at the core of nearly all galaxies and that the mass of each black hole is proportional to that of

(C) exist at the core of nearly all galaxies, and that the mass of each black hole is proportional to

(D) exists at the core of nearly all galaxies, and that the mass of each black hole is proportional to that of

(E) exists at the core of nearly all galaxies and the mass of each black hole is proportional to that of
Show more

First, we can IGNORE the appositive phrase "regions of space in which matter is so concentrated and the pull of gravity so powerful that nothing, not even light, can emerge from them"

So, we can read the original sentence as: Scientists have recently found evidence that black holes exist at the core of nearly all galaxies and the mass of each black hole is proportional to its host galaxy.

Scanning the answer choices, we see EXIST vs EXISTS
Since the verb must agree with BLACK HOLES (plural), we need the plural verb EXIST.
ELIMINATE D and E

Next, notice that the scientists discovered two things:
#1) that black holes exist at the core of nearly all galaxies
#2) the mass of each black hole is proportional to its host galaxy.

Item #1 is a relative clause beginning with THAT.
So, to maintain parallelism, item #2 must also begin with THAT

In other words, we need: Scientists have recently found evidence THAT black holes exist at the core of nearly all galaxies and THAT the mass of each black hole is proportional to its host galaxy.
ELIMINATE A.

We're left with answer choices B and C
B) Scientists have recently found evidence that black holes exist at the core of nearly all galaxies and that the mass of each black hole is proportional to that of its host galaxy.
We are comparing the MASS of each black hole to THAT (aka the MASS) of its host galaxy.
Since we're logically comparing masses, we can KEEP B for now

C) Scientists have recently found evidence that black holes exist at the core of nearly all galaxies, and that the mass of each black hole is proportional to its host galaxy.
Here, we're comparing the MASS of each black hole to a HOST GALAXY.
This comparison makes no sense.
ELIMINATE C

By the process of elimination, the correct answer is B

Cheers,
Brent
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Scientists have recently found evidence that black holes—regions of sp 04 Apr 2019, 12:36
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Hello Everyone!

This is a great example of a GMAT question that focuses on parallelism and subject-verb agreement! Let's start by taking a quick look at the original question, and highlighting any major differences between the options in orange:

Scientists have recently found evidence that black holes—regions of space in which matter is so concentrated and the pull of gravity so powerful that nothing, not even light, can emerge from them—probably exist at the core of nearly all galaxies and the mass of each black hole is proportional to its host galaxy.

(A) exist at the core of nearly all galaxies and the mass of each black hole is proportional to
(B) exist at the core of nearly all galaxies and that the mass of each black hole is proportional to that of
(C) exist at the core of nearly all galaxies, and that the mass of each black hole is proportional to
(D) exists at the core of nearly all galaxies, and that the mass of each black hole is proportional to that of
(E) exists at the core of nearly all galaxies and the mass of each black hole is proportional to that of

After taking a quick glance over the options, 2 major differences jumped out:

1. exist vs. exists (subject-verb agreement)
2. to vs. to that of (parallelism)

Let's start with #1 on our list: subject-verb agreement. If we look at the entire sentence, we should be able to identify the subject that matches up with the verb "exist/exists" pretty quickly:

Scientists have recently found evidence that black holes—regions of space in which matter is so concentrated and the pull of gravity so powerful that nothing, not even light, can emerge from them—probably exist at the core of nearly all galaxies and the mass of each black hole is proportional to its host galaxy.

Since the subject "black holes" is plural, we need to make sure the verb we use is also plural:

(A) exist at the core of nearly all galaxies and the mass of each black hole is proportional to
(B) exist at the core of nearly all galaxies and that the mass of each black hole is proportional to that of
(C) exist at the core of nearly all galaxies, and that the mass of each black hole is proportional to
(D) exists at the core of nearly all galaxies, and that the mass of each black hole is proportional to that of
(E) exists at the core of nearly all galaxies and the mass of each black hole is proportional to that of

We can eliminate options D & E because the singular verb "exists" doesn't match the plural subject "black holes." Pretty easy, right?

Now let's tackle #2 on our list: parallelism. This sentence is comparing two items, and we need to make sure that they are parallel in type. To make this easier to spot, we'll add the rest of the comparison to each option for you. Here's how they break down:

(A) exist at the core of nearly all galaxies and the mass of each black hole is proportional to its host galaxy.

This is INCORRECT because it's comparing mass to galaxy, which aren't the same thing at all!

(B) exist at the core of nearly all galaxies and that the mass of each black hole is proportional to that of its host galaxy.

This is CORRECT! It's clear that by adding in the phrase "that of," we're now comparing the mass of each black hole to the mass of its host galaxy, which is parallel.

(C) exist at the core of nearly all galaxies, and that the mass of each black hole is proportional to its host galaxy.

This is INCORRECT because it's trying to compare mass to galaxies, which aren't parallel.


There you have it - option B is the correct choice! It uses proper parallel structure to compare two items, and it doesn't have any subject-verb agreement issues!


Don't study for the GMAT. Train for it.
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Scientists have recently found evidence that black holes—regions of sp Updated on: 26 Mar 2020, 23:36
Originally posted by unraveled on 18 Apr 2019, 21:16.
Last edited by unraveled on 26 Mar 2020, 23:36, edited 1 time in total.
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Quote:
Scientists have recently found evidence that black holes—regions of space in which matter is so concentrated and the pull of gravity so powerful that nothing, not even light, can emerge from them—probably exist at the core of nearly all galaxies and the mass of each black hole is proportional to its host galaxy.

(A) exist at the core of nearly all galaxies and the mass of each black hole is proportional to
(B) exist at the core of nearly all galaxies and that the mass of each black hole is proportional to that of
(C) exist at the core of nearly all galaxies, and that the mass of each black hole is proportional to
(D) exists at the core of nearly all galaxies, and that the mass of each black hole is proportional to that of
(E) exists at the core of nearly all galaxies and the mass of each black hole is proportional to that of

OG16 SC128
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-Three things i observed
1. S-V agreement(black holes - exist/exists)
2. Parallelism(and)
3. Meaning(recent discovery v/s fact)
4. Comparison(Mass of black holes to host galaxy)

Based on S-V agreement D & E are out(plural subject and singular verb). Parallelism and Meaning are interdependent here since parallelism create a different meaning(that Black holes existence is a recent discovery and proportionality of black hole mass to host galaxy is a known fact which is not) which is vague certainly because without knowing about apples one can't say anything about its taste. This becomes easier to understand by hiding the sentence part between two dashes. Lastly, the Comparison just nails things down to one option i.e. B.

Option-(B) Correct.

Hope this is clear enough understanding on my part though i first saw comparison and then realized the meaning of sentence, hence marked B. Definitely, would want to know/see the meaning as early as possible. Trying my best.

Comments and inputs are most welcomed.
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Scientists have recently found evidence that black holes—regions of sp 19 Apr 2019, 00:46
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Welcome to the forum and wonderful and masterly analysis. One more kudos to you.

May I take your okay to make some observations on your analysis? I presume so.
Quote:

1. -Three things i observed
1. S-V agreement(black holes - exist/exists)
2. Parallelism(and)
3. Meaning(recent discovery v/s fact)
4. Comparison(Mass of black holes to host galaxy)

Based on S-V agreement D & E are out(plural subject and singular verb). Parallelism and Meaning are interdependent here since parallelism create a different meaning(that Black holes existence is a recent discovery and proportionality of black hole mass to host galaxy is a known fact which is not) which is vague certainly because without knowing about apples one can't say anything about its taste. This becomes easier to understand by hiding the sentence part between two dashes. Lastly, the Comparison just nails things down to one option i.e. B.
Show more

Option-(B) Correct.

I think you have observed in fact four things. Let me now change the order of the observations.

1. S.V agreement --- D and E are gone.

2. comparison ---------A and C gone

3. Meaning ------------ Nothing more to discard. This point is academic and in fact redundant.
4. Parallelism: ------- Same treatment as for point 3.

I am not saying in the least that meaning and parallelism are not important. However, in the context, one may stop at point two and if one can afford the luxury of spare time in the exam, one may verify with the other points.

My comments are related only to the strategy for GMAT and not intended against one's quest for knowledge.
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Scientists have recently found evidence that black holes—regions of sp 24 Jun 2019, 00:24
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Quote:
(A) exist at the core of nearly all galaxies and the mass of each black hole is proportional to

(A) doesn’t seem all that bad. It certainly sounds fine, but there’s a problem with the parallelism and meaning.

Before we get into that, consider the following:

  • I believe that Santa Claus is real and that the Knicks will win the 2018 NBA title. → We have two parallel phrases (subordinate clauses, if you like jargon) that begin with “that.” And that’s great: it’s super-clear that these are two things that I believe.
  • I believe that Santa Claus is real and the Knicks will win the 2018 NBA title. → Now the parallelism is different. Without “that”, we just have two parallel, independent clauses: “I believe that Santa Claus is real” and “the Knicks will win the NBA title.” That changes the meaning: now, the sentence doesn’t connect “I believe” with “the Knicks will win the NBA title.” And it seems that the latter clause is a fact, rather than something I BELIEVE is true.

We have a similar situation in (A). On both sides of the “and”, we have full, independent clauses:

  • “Scientists have recently found evidence that black holes exist at the core of nearly all galaxies…”
  • ”…the mass of each black hole is proportional to its host galaxy.”

Here’s the problem: the second independent clause is just a completely separate statement. The second clause (“the mass of each black hole is proportional…”) seems to be a separate fact; without “that” in front of that clause, it’s not clear that scientists have found evidence to support the statement. The statement is just a separate thing.

There’s also a comparison problem with (A). We have “the mass of each black hole is proportional to its host galaxy”, which is illogical: the mass of each black hole might be proportional to the mass of its host galaxy, but it’s weird to suggest that the mass is somehow proportional to the galaxy itself.

So we have a couple of (admittedly somewhat subtle) reasons to eliminate (A).

Quote:
(B) exist at the core of nearly all galaxies and that the mass of each black hole is proportional to that of
Now the parallelism is better: “Scientists have found evidence that black holes… probably exist… and that the mass of each black hole is proportional…” Cool: now it’s clear that scientists have found evidence for these two things.

The other thing that should jump out at you is the phrase “that of.” “That” is a singular pronoun in this situation (more on “that”), and it clearly refers back to “mass” in (B). And that’s great: “…the mass of each black hole is proportional to the mass of its host galaxy.”

So we can keep (B).

Quote:
(C) exist at the core of nearly all galaxies, and that the mass of each black hole is proportional to
(C) is identical to (B), except that the phrase “that of” is missing. And as we mentioned in the explanation for (A), that’s a problem: literally, (C) says that “the mass of each black hole is proportional to its host galaxy”, and that’s not quite right: the mass of the black hole is proportional to the mass of the host galaxy – not to the galaxy itself.

So (C) is out.

Quote:
(D) exists at the core of nearly all galaxies, and that the mass of each black hole is proportional to that of
(D) is identical to (B), except for one little problem: “Scientists have found evidence that black holes… exists…” That’s a wonderfully clear subject-verb error, and we can eliminate (D).

Quote:
(E) exists at the core of nearly all galaxies and the mass of each black hole is proportional to that of
(E) has exactly the same subject-verb error as (D): “Scientists have found evidence that black holes… exists…” Plus, the parallelism is a problem, because “and” isn’t followed with “that” – see the explanation for (A) for more on this issue.

So (E) is out, and (B) is our answer.
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Hello GMATNinja,

Can you help me understand what "its" refer to in the non-underlined part of the last 3 words?

I was confused b/w Black hole & Mass. In the same option B, we have black hole singular too.

I rewrote the second || that clause of option B as " that the mass of each black hole is proportional to that(mass) of its(black hole's) host galaxy."

Considering this, I eliminated option B.

After reading your explanation, i understand that I was wrong but how do we ensure that we do not repeat such mistake?
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Scientists have recently found evidence that black holes—regions of sp 26 Jun 2019, 18:53
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Quote:
Hello GMATNinja,

Can you help me understand what "its" refer to in the non-underlined part of the last 3 words?

I was confused b/w Black hole & Mass. In the same option B, we have black hole singular too.

I rewrote the second || that clause of option B as " that the mass of each black hole is proportional to that(mass) of its(black hole's) host galaxy."

Considering this, I eliminated option B.

After reading your explanation, i understand that I was wrong but how do we ensure that we do not repeat such mistake?
Show more
I'm worried that I don't quite understand your question -- it sounds like your interpretation of the pronouns in (B) was 100% correct!

It makes sense to write that the mass of a black hole is proportional to the mass of the black hole's host galaxy. We know that "its" has to refer to a singular antecedent and the closest singular antecedent here is "black hole."

Did you somehow get confused about the meaning, and decide that it was illogical somehow?

Sorry that I'm not more helpful on this, but it sounds like you were on the right track.
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Scientists have recently found evidence that black holes—regions of sp 11 Oct 2019, 02:52
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Dear GMATNinja, I think up another reason to eliminate option C: the use of the comma after "galaxy" is incorrect because if we have only 2 clauses after "found evidence that", we don't need to have a comma before "and that". The sentence should read: "Scientists have recently found evidence that black holes probably exist at the core ... and that the mass of each black hole is proportional to its host galaxy".

However, if the list consists of 3 or more items, a comma is needed: A, B, and C.

Is my thinking correct?
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Scientists have recently found evidence that black holes—regions of sp 19 Oct 2019, 06:31
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Dear GMATNinja, I think up another reason to eliminate option C: the use of the comma after "galaxy" is incorrect because if we have only 2 clauses after "found evidence that", we don't need to have a comma before "and that". The sentence should read: "Scientists have recently found evidence that black holes probably exist at the core ... and that the mass of each black hole is proportional to its host galaxy".

However, if the list consists of 3 or more items, a comma is needed: A, B, and C.

Is my thinking correct?
Show more
It's true that if you have two modifying clauses connected by "and" you usually won't find a comma between them, but this isn't an ironclad rule, so in general, I'd be wary of eliminating an answer choice on this basis.

That's especially true in this case, since we have an illogical comparison in (C): the mass of the black hole should be proportional to the mass of the host galaxy, not to the galaxy itself.

More generally, you'll want to eliminate answer choices based on definitive errors, and the absence or presence of a comma is almost never a definitive error. So if you ever find yourself agonizing over whether a comma is used appropriately, look for other more concrete issues to use as decision points instead.

I hope that helps!
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Scientists have recently found evidence that black holes—regions of sp 07 Nov 2019, 08:02
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Hey GMATNinja

Considering Choice A: Wouldn´t it also be necessary to use a comma before the end? Since it is another main clause?

Thanks for the clarification!

GMATNinja
Quote:
(A) exist at the core of nearly all galaxies and the mass of each black hole is proportional to

(A) doesn’t seem all that bad. It certainly sounds fine, but there’s a problem with the parallelism and meaning.

Before we get into that, consider the following:

  • I believe that Santa Claus is real and that the Knicks will win the 2018 NBA title. → We have two parallel phrases (subordinate clauses, if you like jargon) that begin with “that.” And that’s great: it’s super-clear that these are two things that I believe.
  • I believe that Santa Claus is real and the Knicks will win the 2018 NBA title. → Now the parallelism is different. Without “that”, we just have two parallel, independent clauses: “I believe that Santa Claus is real” and “the Knicks will win the NBA title.” That changes the meaning: now, the sentence doesn’t connect “I believe” with “the Knicks will win the NBA title.” And it seems that the latter clause is a fact, rather than something I BELIEVE is true.

We have a similar situation in (A). On both sides of the “and”, we have full, independent clauses:

  • “Scientists have recently found evidence that black holes exist at the core of nearly all galaxies…”
  • ”…the mass of each black hole is proportional to its host galaxy.”

Here’s the problem: the second independent clause is just a completely separate statement. The second clause (“the mass of each black hole is proportional…”) seems to be a separate fact; without “that” in front of that clause, it’s not clear that scientists have found evidence to support the statement. The statement is just a separate thing.

There’s also a comparison problem with (A). We have “the mass of each black hole is proportional to its host galaxy”, which is illogical: the mass of each black hole might be proportional to the mass of its host galaxy, but it’s weird to suggest that the mass is somehow proportional to the galaxy itself.

So we have a couple of (admittedly somewhat subtle) reasons to eliminate (A).

Quote:
(B) exist at the core of nearly all galaxies and that the mass of each black hole is proportional to that of
Now the parallelism is better: “Scientists have found evidence that black holes… probably exist… and that the mass of each black hole is proportional…” Cool: now it’s clear that scientists have found evidence for these two things.

The other thing that should jump out at you is the phrase “that of.” “That” is a singular pronoun in this situation (more on “that” in this article), and it clearly refers back to “mass” in (B). And that’s great: “…the mass of each black hole is proportional to the mass of its host galaxy.”

So we can keep (B).

Quote:
(C) exist at the core of nearly all galaxies, and that the mass of each black hole is proportional to
(C) is identical to (B), except that the phrase “that of” is missing. And as we mentioned in the explanation for (A), that’s a problem: literally, (C) says that “the mass of each black hole is proportional to its host galaxy”, and that’s not quite right: the mass of the black hole is proportional to the mass of the host galaxy – not to the galaxy itself.

So (C) is out.

Quote:
(D) exists at the core of nearly all galaxies, and that the mass of each black hole is proportional to that of
(D) is identical to (B), except for one little problem: “Scientists have found evidence that black holes… exists…” That’s a wonderfully clear subject-verb error, and we can eliminate (D).

Quote:
(E) exists at the core of nearly all galaxies and the mass of each black hole is proportional to that of
(E) has exactly the same subject-verb error as (D): “Scientists have found evidence that black holes… exists…” Plus, the parallelism is a problem, because “and” isn’t followed with “that” – see the explanation for (A) for more on this issue.

So (E) is out, and (B) is our answer.
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Scientists have recently found evidence that black holes—regions of sp 30 Nov 2019, 17:36
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philippi
Hey GMATNinja

Considering Choice A: Wouldn´t it also be necessary to use a comma before the end? Since it is another main clause?

Thanks for the clarification!
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Generally speaking, you're correct: if we wanted to have two parallel, independent clauses, we would need to connect them with a comma and a conjunction ("and") -- not just "and." For example, this would generally be considered correct:

    Scientists have found evidence that black holes exist, and I sincerely hope that my lunch doesn't vanish into one before I have a chance to eat it. :shocked

More broadly, though, I wouldn't recommend wasting any energy worrying about comma usage on the GMAT. For starters, it's very, very rare that the presence or absence of a comma is a deciding factor on GMAT SC questions. Also, the rules for commas aren't generally absolute rules -- here's a post that discusses one example of the grey area in comma "rules."

For whatever it's worth, even with a comma, choice (A) would still have the issues described in this post.

I hope this helps!
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Quote:
(A) exist at the core of nearly all galaxies and the mass of each black hole is proportional to

(A) doesn’t seem all that bad. It certainly sounds fine, but there’s a problem with the parallelism and meaning.

Before we get into that, consider the following:

  • I believe that Santa Claus is real and that the Knicks will win the 2018 NBA title. → We have two parallel phrases (subordinate clauses, if you like jargon) that begin with “that.” And that’s great: it’s super-clear that these are two things that I believe.
  • I believe that Santa Claus is real and the Knicks will win the 2018 NBA title. → Now the parallelism is different. Without “that”, we just have two parallel, independent clauses: “I believe that Santa Claus is real” and “the Knicks will win the NBA title.” That changes the meaning: now, the sentence doesn’t connect “I believe” with “the Knicks will win the NBA title.” And it seems that the latter clause is a fact, rather than something I BELIEVE is true.

We have a similar situation in (A). On both sides of the “and”, we have full, independent clauses:

  • “Scientists have recently found evidence that black holes exist at the core of nearly all galaxies…”
  • ”…the mass of each black hole is proportional to its host galaxy.”

Here’s the problem: the second independent clause is just a completely separate statement. The second clause (“the mass of each black hole is proportional…”) seems to be a separate fact; without “that” in front of that clause, it’s not clear that scientists have found evidence to support the statement. The statement is just a separate thing.

There’s also a comparison problem with (A). We have “the mass of each black hole is proportional to its host galaxy”, which is illogical: the mass of each black hole might be proportional to the mass of its host galaxy, but it’s weird to suggest that the mass is somehow proportional to the galaxy itself.

So we have a couple of (admittedly somewhat subtle) reasons to eliminate (A).

Quote:
(B) exist at the core of nearly all galaxies and that the mass of each black hole is proportional to that of
Now the parallelism is better: “Scientists have found evidence that black holes… probably exist… and that the mass of each black hole is proportional…” Cool: now it’s clear that scientists have found evidence for these two things.

The other thing that should jump out at you is the phrase “that of.” “That” is a singular pronoun in this situation (more on “that” in this article), and it clearly refers back to “mass” in (B). And that’s great: “…the mass of each black hole is proportional to the mass of its host galaxy.”

So we can keep (B).

Quote:
(C) exist at the core of nearly all galaxies, and that the mass of each black hole is proportional to
(C) is identical to (B), except that the phrase “that of” is missing. And as we mentioned in the explanation for (A), that’s a problem: literally, (C) says that “the mass of each black hole is proportional to its host galaxy”, and that’s not quite right: the mass of the black hole is proportional to the mass of the host galaxy – not to the galaxy itself.

So (C) is out.

Quote:
(D) exists at the core of nearly all galaxies, and that the mass of each black hole is proportional to that of
(D) is identical to (B), except for one little problem: “Scientists have found evidence that black holes… exists…” That’s a wonderfully clear subject-verb error, and we can eliminate (D).

Quote:
(E) exists at the core of nearly all galaxies and the mass of each black hole is proportional to that of
(E) has exactly the same subject-verb error as (D): “Scientists have found evidence that black holes… exists…” Plus, the parallelism is a problem, because “and” isn’t followed with “that” – see the explanation for (A) for more on this issue.

So (E) is out, and (B) is our answer.
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Thanks Charles, for the detailed explanation.
Apart from other errors in option C, Can I also say that the comma before "and" is incorrectly placed, and it signifies that we need two ICs to be connected.
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Scientists have recently found evidence that black holes—regions of sp 28 May 2020, 23:03
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Quote:
Thanks Charles, for the detailed explanation.
Apart from other errors in option C, Can I also say that the comma before "and" is incorrectly placed, and it signifies that we need two ICs to be connected.
Show more

Hi Adi88,

The rule you are trying to apply is that two independent clauses MUST be joined by a comma and a FANBOYS conjunction. However, sometimes people take it to mean that whenever you have a comma and a FANBOYS conjunction, there should be two independent clauses joined to each other. This understanding is not correct.

You can use "comma +FANBOYS" to join two or more elements in a list as well - elements such nouns, adjectives, subordinate clauses etc.. Usually, however, if the list has two elements placed close to each other, you don't use a comma before the FANBOYS conjunction.

For example:

1. I like to eat apples and oranges.

2. I like to eat apples that my father gets from the local farmers' market or from the health-food store down the lane, and bananas from Uncle Harry's farm.


In the first sentence above, you won't put a comma before the "and" because the two elements in the list (apples and oranges) are placed quite close to each other, BUT look at the second sentence. The two elements "apples................., and bananas" are separated from each other with a lot of information in between them. IN such a case, the use of comma before "and bananas" just makes for a smoother reading experience and hence is allowed.


Does that help?


Cheers!

NS
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Scientists have recently found evidence that black holes—regions of sp 29 May 2020, 08:55
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neetis5
Quote:
Thanks Charles, for the detailed explanation.
Apart from other errors in option C, Can I also say that the comma before "and" is incorrectly placed, and it signifies that we need two ICs to be connected.

Hi Adi88,

The rule you are trying to apply is that two independent clauses MUST be joined by a comma and a FANBOYS conjunction. However, sometimes people take it to mean that whenever you have a comma and a FANBOYS conjunction, there should be two independent clauses joined to each other. This understanding is not correct.

You can use "comma +FANBOYS" to join two or more elements in a list as well - elements such nouns, adjectives, subordinate clauses etc.. Usually, however, if the list has two elements placed close to each other, you don't use a comma before the FANBOYS conjunction.

For example:

1. I like to eat apples and oranges.

2. I like to eat apples that my father gets from the local farmers' market or from the health-food store down the lane, and bananas from Uncle Harry's farm.


In the first sentence above, you won't put a comma before the "and" because the two elements in the list (apples and oranges) are placed quite close to each other, BUT look at the second sentence. The two elements "apples................., and bananas" are separated from each other with a lot of information in between them. IN such a case, the use of comma before "and bananas" just makes for a smoother reading experience and hence is allowed.


Does that help?


Cheers!

NS
Show more

Dear NS,
At the outset, thank you for the reply.

In the second sentence, highlighted above, as far as I understand adding the comma before "and", i.e. "..down the lane, and bananas from Uncle...", doesn't make any difference. The sentence is pretty clear w/o the comma.

May I request you to send me the source for the grammar rule, you mentioned above, rule that highlights the need for comma in cases wherein we have two elements in parallel to each other, and the first element is followed by a long modifier.

Regards,
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Scientists have recently found evidence that black holes—regions of sp 30 May 2020, 04:38
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neetis5
Quote:
Thanks Charles, for the detailed explanation.
Apart from other errors in option C, Can I also say that the comma before "and" is incorrectly placed, and it signifies that we need two ICs to be connected.

Hi Adi88,

The rule you are trying to apply is that two independent clauses MUST be joined by a comma and a FANBOYS conjunction. However, sometimes people take it to mean that whenever you have a comma and a FANBOYS conjunction, there should be two independent clauses joined to each other. This understanding is not correct.

You can use "comma +FANBOYS" to join two or more elements in a list as well - elements such nouns, adjectives, subordinate clauses etc.. Usually, however, if the list has two elements placed close to each other, you don't use a comma before the FANBOYS conjunction.

For example:

1. I like to eat apples and oranges.

2. I like to eat apples that my father gets from the local farmers' market or from the health-food store down the lane, and bananas from Uncle Harry's farm.


In the first sentence above, you won't put a comma before the "and" because the two elements in the list (apples and oranges) are placed quite close to each other, BUT look at the second sentence. The two elements "apples................., and bananas" are separated from each other with a lot of information in between them. IN such a case, the use of comma before "and bananas" just makes for a smoother reading experience and hence is allowed.


Does that help?


Cheers!

NS

Dear NS,
At the outset, thank you for the reply.

In the second sentence, highlighted above, as far as I understand adding the comma before "and", i.e. "..down the lane, and bananas from Uncle...", doesn't make any difference. The sentence is pretty clear w/o the comma.

May I request you to send me the source for the grammar rule, you mentioned above, rule that highlights the need for comma in cases wherein we have two elements in parallel to each other, and the first element is followed by a long modifier.

Regards,
Show more

Hi Adi88,

Thank you for acknowledging my response. :)

The intention behind citing example sentence No. 2 was to show you that how a comma before a FANBOY conjunction can have other uses as well, uses other than joining two independent clauses.

Furthermore, I deliberately avoided the word "rule / need" for the use of the "comma" before the "and" in the second example sentence. I wrote that such usage is allowed (acceptable). This means that it is the discretion of the writer in such a case. So, it's absolutely fine that you found the comma in the second example sentence superfluous, but is it wrong to put it there in the first place? The answer is NO.

Please take a look at this Official Question : https://gmatclub.com/forum/there-are-several-ways-to-build-solid-walls-using-just-mud-or-clay-bu-27542.html#p184853

You will see that the correct answer too employs the usage that I have in example sentence 2.

Does that help?

Cheers!

NS
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Scientists have recently found evidence that black holes—regions of sp 06 Jun 2020, 11:47
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neetis5
Quote:
Thanks Charles, for the detailed explanation.
Apart from other errors in option C, Can I also say that the comma before "and" is incorrectly placed, and it signifies that we need two ICs to be connected.

Hi Adi88,

The rule you are trying to apply is that two independent clauses MUST be joined by a comma and a FANBOYS conjunction. However, sometimes people take it to mean that whenever you have a comma and a FANBOYS conjunction, there should be two independent clauses joined to each other. This understanding is not correct.

You can use "comma +FANBOYS" to join two or more elements in a list as well - elements such nouns, adjectives, subordinate clauses etc.. Usually, however, if the list has two elements placed close to each other, you don't use a comma before the FANBOYS conjunction.

For example:

1. I like to eat apples and oranges.

2. I like to eat apples that my father gets from the local farmers' market or from the health-food store down the lane, and bananas from Uncle Harry's farm.


In the first sentence above, you won't put a comma before the "and" because the two elements in the list (apples and oranges) are placed quite close to each other, BUT look at the second sentence. The two elements "apples................., and bananas" are separated from each other with a lot of information in between them. IN such a case, the use of comma before "and bananas" just makes for a smoother reading experience and hence is allowed.


Does that help?


Cheers!

NS

Dear NS,
At the outset, thank you for the reply.

In the second sentence, highlighted above, as far as I understand adding the comma before "and", i.e. "..down the lane, and bananas from Uncle...", doesn't make any difference. The sentence is pretty clear w/o the comma.

May I request you to send me the source for the grammar rule, you mentioned above, rule that highlights the need for comma in cases wherein we have two elements in parallel to each other, and the first element is followed by a long modifier.

Regards,
Show more
Thanks neetis5 for the awesome reply!

Adi88, there is no black and white "rule" for the case you described. As suggested by neetis5, it's just a matter of clarity: the comma(s) might make for a "smoother reading experience".

Bottom line: if you have two independent clauses, you need the comma+conjunction (or a semicolon). But just because you have a comma+conjunction does NOT necessarily mean you'll need an independent clause on either side! The GMAT is fairly lenient when it comes to comma usage, so you'll want to look for other decision points.
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Quote:
(A) exist at the core of nearly all galaxies and the mass of each black hole is proportional to

(A) doesn’t seem all that bad. It certainly sounds fine, but there’s a problem with the parallelism and meaning.

Before we get into that, consider the following:

  • I believe that Santa Claus is real and that the Knicks will win the 2018 NBA title. → We have two parallel phrases (subordinate clauses, if you like jargon) that begin with “that.” And that’s great: it’s super-clear that these are two things that I believe.
  • I believe that Santa Claus is real and the Knicks will win the 2018 NBA title. → Now the parallelism is different. Without “that”, we just have two parallel, independent clauses: “I believe that Santa Claus is real” and “the Knicks will win the NBA title.” That changes the meaning: now, the sentence doesn’t connect “I believe” with “the Knicks will win the NBA title.” And it seems that the latter clause is a fact, rather than something I BELIEVE is true.

We have a similar situation in (A). On both sides of the “and”, we have full, independent clauses:

  • “Scientists have recently found evidence that black holes exist at the core of nearly all galaxies…”
  • ”…the mass of each black hole is proportional to its host galaxy.”

Here’s the problem: the second independent clause is just a completely separate statement. The second clause (“the mass of each black hole is proportional…”) seems to be a separate fact; without “that” in front of that clause, it’s not clear that scientists have found evidence to support the statement. The statement is just a separate thing.

There’s also a comparison problem with (A). We have “the mass of each black hole is proportional to its host galaxy”, which is illogical: the mass of each black hole might be proportional to the mass of its host galaxy, but it’s weird to suggest that the mass is somehow proportional to the galaxy itself.

So we have a couple of (admittedly somewhat subtle) reasons to eliminate (A).

Quote:
(B) exist at the core of nearly all galaxies and that the mass of each black hole is proportional to that of
Now the parallelism is better: “Scientists have found evidence that black holes… probably exist… and that the mass of each black hole is proportional…” Cool: now it’s clear that scientists have found evidence for these two things.

The other thing that should jump out at you is the phrase “that of.” “That” is a singular pronoun in this situation (more on “that” in this article), and it clearly refers back to “mass” in (B). And that’s great: “…the mass of each black hole is proportional to the mass of its host galaxy.”

So we can keep (B).

Quote:
(C) exist at the core of nearly all galaxies, and that the mass of each black hole is proportional to
(C) is identical to (B), except that the phrase “that of” is missing. And as we mentioned in the explanation for (A), that’s a problem: literally, (C) says that “the mass of each black hole is proportional to its host galaxy”, and that’s not quite right: the mass of the black hole is proportional to the mass of the host galaxy – not to the galaxy itself.

So (C) is out.

Quote:
(D) exists at the core of nearly all galaxies, and that the mass of each black hole is proportional to that of
(D) is identical to (B), except for one little problem: “Scientists have found evidence that black holes… exists…” That’s a wonderfully clear subject-verb error, and we can eliminate (D).

Quote:
(E) exists at the core of nearly all galaxies and the mass of each black hole is proportional to that of
(E) has exactly the same subject-verb error as (D): “Scientists have found evidence that black holes… exists…” Plus, the parallelism is a problem, because “and” isn’t followed with “that” – see the explanation for (A) for more on this issue.

So (E) is out, and (B) is our answer.
Show more

Hi GMATNinja,

To your example, why can't we understand the sentence in this way:-
I believe that
1)Santa Clause is real
2) Nicks will win.
It then seems totally fine, because then we have two clauses which are parallel. In fact shouldn't it better because we are avoiding unnecessary additional reputation and by doing so makes the sentence more concise.
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Scientists have recently found evidence that black holes—regions of sp 07 Jul 2020, 15:44
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Quote:
Hi GMATNinja,

To your example, why can't we understand the sentence in this way:-
I believe that
1)Santa Clause is real
2) Nicks will win.
It then seems totally fine, because then we have two clauses which are parallel. In fact shouldn't it better because we are avoiding unnecessary additional reputation and by doing so makes the sentence more concise.
Show more
Remember, the distinction here is about differences in meaning and clarity. To see why you might want the second "that," consider another example:

    Tim believes that the Knicks are, in fact, better off without Lebron, Durant and all of the other major free agents who have spurned them over the years because of their culture of chaos and dysfunction and that James Dolan, the greatest rock musician since Jimmy Paige, genuinely thinks he's doing what's best for the team.

This is a long, complicated sentence. Using "that" twice makes it clear, despite the density of the language, that Tim believes two things: 1) the Knicks are better off without good basketball players and 2) James Dolan thinks he's doing what's best for the team.

But now consider how difficult the sentence is to understand without the second "that"

    Tim believes that the Knicks are, in fact, better off without Lebron, Durant, and all of the other major free agents who have spurned them over the years because of their culture of chaos and dysfunction, and James Dolan, the greatest rock musician since Jimmy Paige, genuinely thinks he's doing what's best for the team.

At first, it seems as though the players have spurned the Knicks because of chaos, and dysfunction and James Dolan. If you read it a second time, maybe you arrive at the conclusion that one clause is about what Tim believes (the Knicks are better off without good players) and one clause is about what Jim Dolan thinks (he's doing what's best for the team.) If the writer intended to capture the idea that Tim believes two distinct truths, one about the team, and one about James Dolan, it's very very difficult to see that. At best, this sentence is confusing and ambiguous. And if a sentence is confusing, it doesn't matter if it's more concise. Clarity is far more important.

Put another way, it's not that the first sentence is inherently right and the second inherently wrong; it's that the first sentence is clearer and more logical than the second. This is the point of parallel constructions. They aren't arbitrary rules that exist to torment us. Rather, they're helpful instructions for how to understand and make sense of a sentence.

I hope that helps a bit!
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Gmat Ninja

Please consider this question

 The use of lie detectors is based on the assumption that lying produces emotional reactions in an individual
, in turn, create unconscious physiological ­responses.

So this is an official answer and here that is referring to the the plural noun "emotional reactions", but in the article it clearly says .. replace that with a singlular noun .
I replaced that with , the use ..which was clearly wrong
Kindly help
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