Positing an enormous volcanic explosion at the end of the Permian

Question

Positing an enormous volcanic explosion at the end of the Permian period would explain the presence

(A) account for the presence of the element iridium (originating deep within the earth), and the presence of quartz having been
(B) of the element iridium (originating deep within the earth), and of quartz
(C) the element iridium (originating deep within the earth), and explain the presence of quartz having been
(D) the presence of the element iridium (originating deep within the earth), and explain the presence of quartz
(E) explain the element iridium (originating deep within the earth), and the presence of quartz

elegantm · Accepted Answer

This question tests Parallelism. Parallelism that we need to check may follow either of the 3 below mentioned patterns-
  Pattern 1 -  Explain the presence of X, Y, & Z - Correct
 Pattern 2 -  Explain the presence of X, the presence of Y, & the presence of Z - Correct
 Pattern 3 -  Explain the presence of X, Explain the presence of Y, & Explain the presence of Z - Correct

A) Follows Pattern 2, But use of ACCOUNT FOR is unjustified. Hence Incorrect
B) Follows Pattern 1. Hence Correct
C) Follows mix of Patterns 1, 2, & 3. Hence Incorrect
D) Follows mix of Patterns 2 & 3. Hence Incorrect
E) Follows mix of Patterns 3 & 2. Hence Incorrect

egmat · Answer

Hello somtsat99 , I am just adding my two cents here. When the elements in a parallel list are big phrases, the scope of possible parallel elements also increase by far. Let's take a look at the sentence with the correct answer choice B: Positing an enormous volcanic explosion at the end of the Permian period would explain the presence of a buried crater, of the element iridium (originating deep within the earth), and of quartz shattered by high-impact shock waves. Since all the three elements are prepositional phrases, they are perfectly parallel. Since of has been used in all the three elements, another possible parallel list can be what elegantm has stated in his post as Pattern 1. Hope this helps. :-)

Thanks. Shraddha

ExpertsGlobal5 · Answer

Dear Friends,

Here is a detailed explanation to this question-

Concepts tested here: Parallelism + Verb Forms

• All elements in a list must be parallel.
• In modifying a noun, the past participle implies that the noun took an action that concluded in the past.

A:  The sentence formed by this answer choice fails to maintain parallelism among "explain the presence of a buried crater", "account for the presence of the element iridium (originating deep within the earth)", and "the presence of quartz"; remember, all elements in a list must be parallel. Further, Option A incorrectly uses the present participle ("verb+ing" - "having" in this sentence) phrase "having been shattered" to refer to an action that concluded in the past; remember, the simple past tense is used to refer to events that concluded in the past.

B:   Correct.  The sentence formed by this answer choice correctly maintains parallelism among "of a buried crater", "of the element iridium (originating deep within the earth)", and "of quartz". Further, Option B correctly uses the past participle ("shattered" in this case) to refer to an action that concluded in the past; remember, in modifying a noun, the past participle implies that the noun took an action that concluded in the past.

C:  The sentence formed by this answer choice fails to maintain parallelism among "explain the presence of a buried crater", "the element iridium (originating deep within the earth)", and "explain the presence of quartz"; remember, all elements in a list must be parallel. Further, Option C incorrectly uses the present participle ("verb+ing" - "having" in this sentence) phrase "having been shattered" to refer to an action that concluded in the past; remember, the simple past tense is used to refer to events that concluded in the past.

D:  The sentence formed by this answer choice fails to maintain parallelism among "explain the presence of a buried crater", "the presence of the element iridium (originating deep within the earth)", and "explain the presence of quartz"; remember, all elements in a list must be parallel.

E:  The sentence formed by this answer choice fails to maintain parallelism among "explain the presence of a buried crater", "explain the element iridium (originating deep within the earth)", and "the presence of quartz"; remember, all elements in a list must be parallel.

Hence, B is the best answer choice.

To understand the concept of "Simple Tenses" on GMAT, you may want to watch the following video (~2 minutes):

https://www.youtube.com/watch?v=ATNTtugB9fM

All the best!
Experts' Global Team

Kurtosis · Answer

Topic Tested: Parallelism

Positing an enormous volcanic explosion at the end of the Permian period would explain the presence

A. account for the presence of the element iridium (originating deep within the earth), and the presence of quartz having been - Incorrect. Parallelism error.

B.  of the element iridium  (originating deep within the earth), and  of quartz   - Correct. would explain the presence  of a buried crater ,  of the element iridium , and  of quartz .

C. the element iridium (originating deep within the earth), and explain the presence of quartz having been - Incorrect. would explain the presence of x, y and explain the presence of z is not parallel again.

D. the presence of the element iridium (originating deep within the earth), and explain the presence of quartz - Incorrect. Parallelism error again.

E. explain the element iridium (originating deep within the earth), and the presence of quartz - Incorrect. Parallelism error.

Answer: B

somtsat99 · Answer

But is follows presence of X and Of Y.

Posted from my mobile device

sevenplusplus · Answer

Could someone clarify how D is wrong?

Here is the sentence with D:
Positing an enormous volcanic explosion at the end of the Permian period would explain the presence of a buried crater, the presence of the element iridium (originating deep within the earth), and [would] explain the presence of quartz shattered by high-impact shock waves.

Just before this post, I read:
https://gmatclub.com/forum/your-verbal- ... 46533.html
which suggests not be over fixated with true parallel structure to the hilt.
Shouldn't there be more than just parallelism error for us to eliminate choices?

EducationAisle · Answer

Hi  sevenplusplus , let's look at the sentence with D again:

Positing an enormous volcanic explosion at the end of the Permian period would explain the presence

By the intended meaning of the sentence, hopefully it's clear  would explain  is trying to explain  three  elements. In D, the  repetition  of  the presence  in the second element suggests that the way to do (what we call as)  XYZ deconstruct  is:

Positing an enormous volcanic explosion at the end of the Permian period would explain

i) X: the presence of a buried crater
ii) Y: the presence of the element iridium (originating deep within the earth)
iii) Z: explain the presence of quartz shattered by high-impact shock waves.

Once we have done this deconstruct, the  common  portion of the sentence (in this case  Positing an enormous volcanic explosion at the end of the Permian period would explain ) should  individually  make sense with X, with Y, and with Z.

In D, this common portion is  not  making sense with Z, because the sentence would read:

Positing an enormous volcanic explosion at the end of the Permian period would  explain explain  the presence of quartz shattered by high-impact shock waves .

explain explain  is clearly incorrect.

p.s. Our book    EducationAisle Sentence Correction Nirvana    discusses  this very powerful method of tackling parallelism (XYZ deconstruct)  , its application and examples in significant detail. If someone is interested, PM me your email-id; I can mail the corresponding section.

sevenplusplus · Answer

Thanks for the reply. How do we know that "would explain" is "out" of the XYZ deconstruct? My argument is that it could be considered part of each X, Y, Z.

Sent from my iPhone using  GMAT Club Forum mobile app

EducationAisle · Answer

Sure. So, let's try putting  would explain   within  the XYZ deconstruct.

Positing an enormous volcanic explosion at the end of the Permian period

i) X: would explain the presence of a buried crater
ii) Y: would explain the presence of the element iridium (originating deep within the earth)
iii) Z: would explain explain the presence of quartz shattered by high-impact shock waves.

Again, as is evident, Z ( would  explain explain  the presence... ) is incorrect.

ashygoyal · Answer

Hi Vyshak ,

I have a doubt here. When do we use a comma before 'and'? 
Usually its like a,b and c. 
In what conditions, do we use- a,b, and c? and what's the difference?

Really appreciate if you or anyone on this forum can explain.

Regards,
ashygoyal

EMPOWERgmatVerbal · Answer

Hello Everyone!

This looks like a great example of a GMAT question that focuses on parallel structure! Let's go through each option carefully to narrow them down to the right answer! To get started, here is the original question:

Positing an enormous volcanic explosion at the end of the Permian period would explain the presence

(A) account for the presence of the element iridium (originating deep within the earth), and the presence of quartz having been
(B) of the element iridium (originating deep within the earth), and of quartz
(C) the element iridium (originating deep within the earth), and explain the presence of quartz having been
(D) the presence of the element iridium (originating deep within the earth), and explain the presence of quartz
(E) explain the element iridium (originating deep within the earth), and the presence of quartz

One important sign that we're dealing with parallelism is when the options are part of a list.  Any time you see a list, it's a good idea to start by asking yourself, "Is each item in the list worded/structured similarly?" Let's take a closer look at each option to throw out any answers that aren't parallel. To make it easier to spot, I've included the non-underlined part of the list because everything MUST match that in structure, verb tense, and tone:

(A) would  explain the presence of  a buried crater, 
  account for the presence of  the element iridium (originating deep within the earth), 
 and  the presence of  quartz having been

This option is  NOT PARALLEL  because each item in the list is introduced using a different verb, or none at all: explain / account for / no verb. Therefore, this is  INCORRECT  because it's not parallel.

(B) would explain the presence  of a buried crater , 
  of the element iridium  (originating deep within the earth), 
 and  of quartz

This option is  PARALLEL  because each item is introduced in a similar manner (using the word "of"). It's much simpler and more concise, too! Therefore, this is the  CORRECT  option because it uses parallel structure.

(C) would  explain the presence of  a buried crater, 
 the element iridium (originating deep within the earth), 
 and  explain the presence of  quartz having been

This option is  NOT PARALLEL  because only 2 out of 3 items starts with "explain the presence of." For this to be parallel, all 3 items need to match. Therefore, this is another  INCORRECT  option!

(D) would  explain the presence of  a buried crater, 
  the presence of  the element iridium (originating deep within the earth), 
 and  explain the presence of  quartz

This option is also  NOT PARALLEL  because it only uses the verb "explain" in 2 of 3 items in the list. They're very close to parallel, but not quite good enough! Therefore, this option is  INCORRECT  because it doesn't use parallel structure.

(E) would  explain the presence of  a buried crater, 
  explain  the element iridium (originating deep within the earth), 
 and  the presence of  quartz

This option is  NOT PARALLEL  because each item uses different combinations of the phrases "explain the presence of," "explain," and "the presence of." For this to be parallel, all 3 items need to match. Therefore, this option is  INCORRECT  because it doesn't use parallel structure.

There you go - option B is the correct answer because it's the only one that uses parallel structure!

Don't study for the GMAT. Train for it.

Srik20 · Answer

Hi experts, my doubt is regarding the 'comma+and' construction here. Shouldn't it be an IC ? what am I missing here?

GMATNinja · Answer

Typically, a "comma + and" construction will be used in one of two ways: 1) to separate two independent clauses or 2) to designate the end of a list of elements.

(B) is an example of the second situation. Here's the relevant portion of (B) again: "Positing an enormous volcanic explosion at the end of the Permian period would explain the presence  of a buried crater ,  of the element iridium  (originating deep within the earth), and  of quartz ." The volcanic explosion can explain the presence of three elements: a buried crater, the element, iridium, and quartz. Because we have a list, it's appropriate to use "comma + and" to signal to the reader that the list is complete.

Also, the "rules" governing comma usage can be subtle and subjective, so you don't want to be too rigid when debating whether a comma is appropriate. You won't run across many GMAT questions that explicitly test whether the presence or absence of a comma is correct, so it's best to find more concrete reasons to eliminate answer choices. For more on punctuation on the GMAT, check out  this video .

I hope that helps!

ChiefsFan · Answer

GMATNinja , the original sentence has the word  crater  in italics, and I don't quite understand why. Does it make sense to you?

GMATNinja · Answer

I definitely don't see "crater" in italics on  the original post on this thread , or in my copy of the 2020 OG. Are you looking at something other than the original post or the OG, maybe?

TheUltimateWinner · Answer

EducationAisle 
Hi,
I've a curiosity to know one thing from you about choice D.
 
What if we remove the middle item from the choice D? Is it something like below?
 Positing an enormous volcanic explosion at the end of the Permian period would explain the presence of a buried crater and  (would explain) explain  the presence of quartz shattered by high-impact shock waves.

Thanks__

EducationAisle · Answer

Yeah looks fine from a parallelism perspective, though the duplication of  explain  in the second part, is  redundant .

kadamhari825 · Answer

Hello experts  AjiteshArun   sayantanc2k   EducationAisle   VeritasKarishma

I chose option A on the basis of following reasoning.

I reasoned  account for the presence of the element iridium (originating deep within the earth), and the presence of quartz having been  as noun+noun modifier ( absolute phrase ) modifying  a buried crater  and underlined part is made parallel by connector  ,and  . i understood that option B is correct answer but where i am making mistake in understanding option A?

Thanks and regards.

AjiteshArun · Answer

Hi  kadamhari825 ,

You may have gone for an unlikely meaning, which in turn would have led you to an unlikely structure ( X would  explain  Y ,   account  for A and B ). The problem with this interpretation is that the  buried crater  can't be directly related to the  iridium  and the  shattered quartz . Instead, the intended meaning of this sentence is that there are  three  things that  positing an enormous volcanic explosion  would explain: the buried crater, the presence of iridium from deep within the Earth, and the shattered quartz.

This is the sentence that option A leads to:

1.  {X} would (a)  explain  the presence of a buried crater, (b)  account  for the presence of the element iridium (originating deep within the earth),  and  (c) the  presence  of quartz having been shattered by high-impact shock waves.

Explain  is a verb form (it combines with  would ), and  account  is a verb form as well (again, it combines with  would ).  Presence , however, is a noun, so the elements of the list aren't as parallel as in option B. Option A would have been better if it had three verb forms.

Positing an enormous volcanic explosion at the end of the Permian

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GMAT Sentence Correction (SC - EA only) Questions

Positing an enormous volcanic explosion at the end of the Permian

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