The discovery that Earths inner core rotates independently of and more

Question

The discovery that Earth’s inner  core rotates independently of and more quickly than Earth’s outer layers is responsible for advancing studies of the flow of heat from the inner through the outer planet and of the formation and periodic reversal in direction of Earth’s magnetic field .

(A) core rotates independently of and more quickly than Earth’s outer layers is responsible for advancing studies of the flow of heat from the inner through the outer planet and of the formation and periodic reversal in direction of Earth’s magnetic field

(B) core rotates independently of and more quickly than Earth’s outer layers is responsible for advancing studies of how heat from the inner core flows through the outer planet, and the formation and periodic reversal in direction of Earth’s magnetic field

(C) core rotates independently and more quickly than Earth’s outer layers are responsible for advancing studies of how heat from the inner core flows through the outer planet, and how Earth’s magnetic field forms and the periodic reversal of its direction

(D) core, rotating independently and more quickly than Earth’s outer layers, are responsible for advancing studies of the flow of heat from the inner through the outer planet, and the formation and periodic reversal in direction of Earth’s magnetic field

(E) core, rotating independently of and more quickly than Earth’s outer layers, is responsible for advancing studies of the flow of heat from the inner through the outer planet and of how Earth’s magnetic field forms and the periodic reversal of its direction

https://www.nytimes.com/1996/12/17/science/earth-s-core-a-planet-within-the-planet-is-spun-by-twin-streams-of-molten-iron.html

Most notably, the discovery of the inner core's rotation is advancing studies of  how  heat flows through the planet,  how  the interior evolved over the ages  and how  the Earth's magnetic field forms and periodically reverses.

GMATNinja · Answer

This question popped up on our  Ask Me Anything About SC thread . Reposting it here just in case it helps somebody else:

SC is less about why the correct answer is right than why the incorrect options are wrong. The key here, as Shrey9 notes below, is the parallel construction demanded by the multiple uses of "and," and how this construction shapes the meaning of the sentence.

First, take a look at (A), stripped down:

"The discovery   is responsible for advancing studies  of the flow of heat  from the inner through the outer planet  and of the formation  and periodic reversal in direction of Earth's magnetic field."

Because "of the formation" ("preposition + noun") comes right after "and" we want a similar construction to precede it. In this case, we find "of the flow of heat." Now we want to ask ourselves if these two elements are logically parallel. And it makes perfect sense that the discovery is responsible for advancing studies of two things: (1) of the flow of heat and (2) of the formation and reversal of the earth's magnetic field. So keep (A).

Now compare that with all the other options. (B), (C), and (D) all lack the "of" before "formation." Is the preposition absolutely mandatory in a grammatical sense? No. But because the sentence is so complicated, it becomes very very difficult to see that the discovery is responsible for advancing studies of two separate elements if we don't include "of" before both of them. This confusion is enough to get rid of these options, but if you're skeptical, let's find a more concrete error in each:

Here, the "comma + and" creates the expectation that we're going to be treated to new information, potentially unrelated to what we've seen thus far. Put another way, it sounds as though "the discovery" is responsible only for advancing studies of how heat flows, and then there's this new clause about "the formation." But there's no verb to go with "formation!"

When we look back at the sentence, it appears that the discovery is responsible for "advancing studies" and for "the formation" itself. My physics is a little rusty, but I'm confident that a discovery can't be responsible for the formation of a magnetic field. That's illogical, so get rid of (B).

Both (C) and (D) have the same subject-verb agreement error: " The discovery...  are  responsible ," so those are out.

And here's (E): 
First, it sounds like the "earth's inner core" is itself responsible for advancing studies. Worse, there's no main verb here to go with the subject "the discovery." So this is illogical and ungrammatical. (E) is out, and (A) is our winner.

I hope that helps!

Shivam1809 · Answer

GMATNinja   GMATNinjaTwo 
Hi Guys,

b) core rotates independently of and more quickly than Earth’s outer layers is responsible for advancing studies  of  how heat from the inner core flows through the outer planet, and  the  formation and periodic reversal in direction of Earth’s magnetic field

I am unable to understand why isn't 'of' implied before 'the formation' as well just like it is implied in option A.

Parallelism has been a pain point for me, although i can understand the meaning and recognise the lists but many a times i am just unable to decipher wether the entities are parallel or not. So kindly please elaborate and let me know how do i resolve this parallelism issue.

thanks

GMATNinja · Answer

First off, let's take another look at the parallelism in choice (A):

Both items in the list have the form "of the  ", and the "of" is explicitly restated (not implied). As discussed in  this post , the repeated "of" makes it crystal clear that both items can be tied back to "study": (1) "study of the flow of heat..." and (2) "{study of} the formation/periodic reversal...".

Now let's look at the parallelism in choice (B):

Sure, you can argue that both items share the "of", but notice that, in this case, the two things in the list do NOT have the same structure. The second item consists of a pair of simple nouns ("formation and periodic reversal"), while the first item is a  clause  introduced by "how".

What's worse is that there's  another  way to interpret the parallelism in choice (B):

This interpretation clearly doesn't make much sense. But since "advancing" is an "-ing" word that functions as a noun (a gerund, if you like grammar jargon), it's perfectly reasonable for a reader to assume that "advancing" is parallel to "formation and periodic reversal".

So choice (B) leaves us with two different interpretations. And in the one that makes more sense, the parallelism is off (a "how" clause parallel to "formation and periodic reversal"). In choice (A), the parallelism is spot on  and  the logical meaning is crystal clear, so (A) is a much better option.

For more on why (A) is better than (B), check out  this post .

patto · Answer

GMATNinja 
 VeritasKarishma

am I wrong in saying that D and E are sentence fragments? I mean there is no main verb for the discovery subject

GMATNinja · Answer

Yup, that's correct. The verbs in these two options ("is" and "are") are trapped within the "that" clause, so we don't actually have a main verb for the subject ("discovery").

CrushTHYGMAT · Answer

Bunuel , can you please tag this as a GMAT Prep question? It appeared in my mock today.

Thank you.

Bunuel · Answer

_____________________
Done. Thank you!

rishi02 · Answer

GMATNinja 
 EMPOWERgmatVerbal

While i now understand the reasons why option (b) is incorrect, the highlighted portion in the option (a) continues to throw me off.

The discovery that Earth's inner core rotates independently of and more quickly than Earth's outer layers is responsible for advancing studies of the  flow of heat from the inner through the outer planet  and of the formation and periodic reversal in direction of Earth's magnetic field.

Is ellipsis at play here? Core is implied? Doesn't seem like a very natural construction

EMPOWERgmatVerbal · Answer

Thanks for your question  rishi02 !

While we do agree that this sentence is incredibly long-winded, which might make it confusing for readers, option A is still the best option of the 5 we have to choose from. Since we're only talking about one planet, we can imply that when we refer to the "inner" planet, we're talking about the core. Repeating mention of the core would be more important if we were comparing/contrasting more than one planet.

This is one of the ways the GMAT can be tricky - long, complex sentences with a lot of parts can distract us from the core concepts we need to focus on, which in this case are parallelism and logical construction.

We hope that helps! Feel free to tag us at  EMPOWERgmatVerbal  if you have any other questions!

GmatKnightTutor · Answer

rishi02

While i now understand the reasons why option (b) is incorrect, the highlighted portion in the option (a) continues to throw me off.

The discovery that Earth's inner core rotates independently of and more quickly than Earth's outer layers is responsible for advancing studies of the  flow of heat from the inner through the outer planet  and of the formation and periodic reversal in direction of Earth's magnetic field.

Is ellipsis at play here? Core is implied? Doesn't seem like a very natural construction

The sentence is sort of structured as follows:

The discovery... is responsible for... studies

1) of the flow of heat...
2) of the formation...

Hope that helps.

ExpertsGlobal5 · Answer

Hello  rishi02 ,

We hope this finds you well.

To answer your query, the phrase "from the inner through the outer planet" does not directly refer to the "core"; rather, it simply conveys that the studies that were advanced by a discovery regarding the Earth's inner core are concerned with how heat moved from deeper sections of the planet to outer sections.

We hope this helps.
All the best!
Experts' Global Team

Anshul1223333 · Answer

while talking about parallelism in B]

we see '' discovery is responsible for advancing studies of how heat from the inner core flows and the formation.....

the phrase followed after preposition ''of'' should be a noun?

I heard from somewhere that ''how heat flows from the inner core'' behave as a noun'' Please guide.

if we ingnore the word 'how' is parallelism justified? do we really need another 'of' before the 'formation' to make it parallel?

Can't we assume 'of' to be commom for the items in the list

Moreover, is oxford comma rule strictly followed on GMAC. can we use it for elimination?

RonTargetTestPrep · Answer

The words  who/what/where/when/why/how  have two different functions in the English language in general:
1/ Starting a  question 
2/ Starting a  noun clause  (= a clause—i.e., with a subject+verb in it—that acts as a noun) 
The noun clause here, by the way, represents the answer to the corresponding question. E.g., in the sentence  "I know  what you're thinking " , the noun clause  "what you're thinking"  represents the answer to the question  "What are you thinking?"

GMAT SC sentences, however, are NEVER questions—they're ALWAYS declarative statements. Accordingly,  in GMAT SC, these words  who/what/when/where/why/how  will introduce noun clauses .

There are some additional words of this type that  cannot  introduce a valid question—or that can only do so in heavily stylized/poetic/dramatic language—and that therefore MUST therefore begin a noun clause even in the more general English language.
E.g.,
  whether   (...absolutely CANNOT begin a question; this word  must  begin a noun clause)
  whatever/whoever/whomever/however/wherever/whenever   (...can only begin questions in poetic/dramatic speech; otherwise must begin a noun clause)

RonTargetTestPrep · Answer

The mechanical parallelism is workable either with or without the second "of":
 studies of   X  and  Y  
studies   of X  and  of Y

In this context, it's better to use two instances of "of", for at least two reasons:

• These parallel parts are so long that, without the additional cue provided by the second "of", it's very difficult to recognize them in one read-through of the sentence.

• There's a fairly subtle distinction in meaning: "Studies  of X and Y " implies that X and Y are covered together in each of the studies, whereas "studies  of X and of Y " implies that there are, separately, studies of X and studies of Y.
In this case the 'X' and the 'Y' represent two altogether different scientific subjects, so the latter meaning is more sensible in context.
(No official SC problem will  require  the consideration of subtleties on this level.)

GMAC follows the convention of inserting this comma before "and"/"or" in lists of three or more parallel items.
 X, Y ,  and/or Z  (...NOT "X, Y and/or Z")

I don't think you'll ever have the opportunity to use this for elimination. GMAC will  definitely NOT  write wrong answers containing these sorts of lists WITHOUT the last comma.

In fact, if you see something that LOOKS like that, you should consider it carefully because it's probably a different type of construction altogether.

E.g.,
 In 2010 I married Sarah, my soul mate and my best friend. 
This is "X, Y and Z" in which the "Y and Z" part (my soul mate and my best friend) is a modifier of "X" (Sarah). Obviously I didn't marry three different women at once!

GMATNinja · Answer

Looks like Ron (hi, Ron!) beat us to this one, but in case it helps, check out  this post  for our take on the parallelism in A and B.

Anshul1223333 · Answer

of course, one can't marry three women at once! Thanks for your help

mansianand1234 · Answer

can we say that oxford comma is used incorrectly in B C and E?

GMATNinja · Answer

Well, (C) and (D) are out right away because of the subject-verb agreement error (The discovery... are responsible...). The GMAT is pretty lenient when it comes to comma usage, and we've seen OAs with a comma separating just two things in a list. Generally speaking, if you're unsure about a comma, you're MUCH better off looking for other decision points. In this case, the more important issue is the parallelism in the remaining choices: (A) The discovery is responsible for advancing studies (1) of the flow of heat from the inner through the outer planet and (2) of the formation and periodic reversal in direction of Earth’s magnetic field. (B) The discovery is responsible for advancing studies of (1) how heat from the inner core flows through the outer planet, and (2) the formation and periodic reversal in direction of Earth’s magnetic field (E) The discovery is responsible for advancing studies (1) of the flow of heat from the inner through the outer planet and (2) of how Earth’s magnetic field forms and the periodic reversal of its direction The parallelism in choice (A) is the best ("... studies of X and of Y..."), and, as a result, the meaning is clearer and easier to follow in (A) than in (B) and (E). For more on that, check out this post: https://gmatclub.com/forum/the-discover ... l#p2419284.

mcelroytutoring · Answer

"ABC" Sentence Template: The discovery  that A  has led to studies  of B  and  of C .

Raman109 · Answer

The discovery that Earth’s inner core rotates independently of and more quickly than Earth’s outer layers is responsible for advancing studies of the flow of heat from the inner through the outer planet and of the formation and periodic reversal in direction of Earth’s magnetic field. Option Elimination - This question plays with our minds.

Long sentences, relative clauses, prepositional phrases, and SVs. If we stick to the basics, the question is comparatively easy. (A) core rotates independently of and more quickly than Earth’s outer layers is responsible for advancing studies of the flow of heat from the inner through the outer planet and of the formation and periodic reversal in direction of Earth’s magnetic field. Basic structure - The discovery (subject) relative clause (which is a noun modifier modifying "the discovery") is (verb) responsible for advancing studies prepositional phrase (of the flow) and prepositional phrase (of the formation). Parallelism around "and". Ok. (B) core rotates independently of and more quickly than Earth’s outer layers is responsible for advancing studies of how heat from the inner core flows through the outer planet, and the formation and periodic reversal in direction of Earth’s magnetic field - The discovery (subject) relative clause (which is a noun modifier modifying "the discovery") is (verb) responsible for advancing studies of "the relative clause" (how heat from the inner core flows) and the noun phrase (the formation and periodic reversal). The structure around "and" is not parallel. (C) core rotates independently and more quickly than Earth’s outer layers are responsible for advancing studies of how heat from the inner core flows through the outer planet, and how Earth’s magnetic field forms and the periodic reversal of its direction - SV issue. (D) core, rotating independently and more quickly than Earth’s outer layers, are responsible for advancing studies of the flow of heat from the inner through the outer planet, and the formation and periodic reversal in direction of Earth’s magnetic field - SV issue (E) core, rotating independently of and more quickly than Earth’s outer layers, is responsible for advancing studies of the flow of heat from the inner through the outer planet and of how Earth’s magnetic field forms and the periodic reversal of its direction - The discovery (subject) noun phrase (the structure of a relative clause is broken) is (verb) responsible for advancing studies of "noun phrase" (the flow of heat from the inner) and of the noun clause (how Earth’s magnetic field forms and the periodic). The structure around "and" is not parallel.

The discovery that Earths inner core rotates independently of and more

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The discovery that Earths inner core rotates independently of and more

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