Covering 71 percent of Earth's surface, the oceans play an essential

Question

Covering 71 percent of Earth’s surface, the oceans play an essential role in maintaining the conditions for human existence on land, moderating  temperature by the absorption of heat and carbon dioxide, and giving pure water back to the atmosphere through evaporation
 
(A) Covering 71 percent of Earth’s surface, the oceans play an essential role in maintaining the conditions for human existence on land, moderating

(B) Covering 71 percent of Earth’s surface and playing an essential role in maintaining the conditions for human existence on land, the oceans moderate

(C) The oceans cover 71 percent of Earth’s surface and play an essential role in maintaining conditions for human existence on land, and by moderating

(D) The oceans cover 71 percent of Earth’s surface, play an essential role in mandating the conditions for human existence on land, and moderate

(E) The oceans cover 71 percent of Earth’s surface, playing an essential role in maintaining the conditions for human existence on land, and they moderate

Oceans on Earth

(A) CORRECT

(B) Parallelism ( X and Y )

(C) Sentence Structure / Parallelism ( X and Y )

(D) Parallelism ( X and Y )

(E) Sentence Structure / Parallelism ( X and Y )

First glance

The answers start with either  covering , a modifier, or  the oceans cover , a subject-verb pairing. Pay attention to Sentence Structure and Meaning.
 
  Issues

(1) Sentence Structure / Parallelism:  X and Y

The non-underlined portion of the sentence contains the words  and giving . The word and is a parallelism marker ( X and Y ), so find the X element. In some of the choices, the X and Y elements are part of the core sentence, so examine the core for all five choices.

(A)  The oceans play an essential role in maintaining …, moderating …, and giving …

(B)  The oceans moderate …, and giving …

(C)  The oceans cover … and play …, and by moderating …, and giving …

(D)  The oceans cover …, play …, and moderate …, and giving …

(E)  The oceans cover …, and they moderate …, and giving …

Answer (A) contains a valid core sentence and a list of three parallel modifying items (in the form  X, Y, and Z ) .

The first part of answer (B) is a valid core sentence, but the Y portion of the  X and Y  construction would have to be  give  in order to be parallel to  moderate . Eliminate choice (B) for   faulty parallelism  .

The first part of answer (C) is again a valid core sentence, but the second half is problematic. The construction  and by moderating  implies that a second independent clause (complete sentence) is coming. For example:

She enrolled in school, and by studying hard and participating in class, she will earn top honors.

In answer (C), there is no equivalent to  she will earn top honors . Answer (C) is the equivalent of  she enrolled in school, and by studying hard and participating in class . Eliminate (C) because it is an   incomplete sentence  .

Answer (D) is especially tricky because just the underlined portion contains a completely valid  X, Y, and Z  structure. However, the sentence contains no X element to go with the non-underlined and giving at the end of the sentence. Eliminate choice (D) for   faulty parallelism  .

Likewise, choice (E) does not contain a valid X element to pair with the non-underlined  and giving . (Note: the  –ing  words  playing  and  maintaining  earlier in this choice cannot be the X element to pair with  giving  because they are part of a separate clause. The X element has to appear in the same clause as the Y element, sometime after the words  and they moderate .) Eliminate choice (E).
 
  The Correct Answer

Correct answer (A) has a valid core sentence and a properly-constructed list of three parallel items.

EMPOWERgmatVerbal · Accepted Answer

Hello Everyone!

This is a great example of a GMAT question that focuses on  parallelism ! Let's start by looking at the original question, and highlight any major differences between the options in  orange :

Covering 71 percent of Earth’s surface, the oceans play an essential role in maintaining the conditions for human existence on land, moderating  temperature by the absorption of heat and carbon dioxide, and giving pure water back to the atmosphere through evaporation.

(A)  Covering  71 percent of Earth’s surface, the oceans play an essential role in maintaining the conditions for human existence on land,  moderating 
(B)  Covering  71 percent of Earth’s surface and playing an essential role in maintaining the conditions for human existence on land,  the oceans moderate 
(C)  The oceans cover  71 percent of Earth’s surface and play an essential role in maintaining conditions for human existence on land,  and by moderating 
(D)  The oceans cover  71 percent of Earth’s surface, play an essential role in mandating the conditions for human existence on land,  and moderate 
(E)  The oceans cover  71 percent of Earth’s surface, playing an essential role in maintaining the conditions for human existence on land,  and they moderate

Since we already know this sentence focuses on  parallelism , let's stick with that for now. We need to make sure that everything tied to the role of oceans on Earth uses parallel structure or wording.

To help us figure out which method of parallel structure or wording we should go with, we should first check to see if any other part of the list is not underlined.  If it's not underlined, it cannot change. That means we MUST make everything else in the sentence match the non-underlined part! Here is the original sentence:

Covering 71 percent of Earth’s surface, the oceans play an essential role in maintaining the conditions for human existence on land, moderating  temperature by the absorption of heat and carbon dioxide,  and giving pure water back to the atmosphere through evaporation.

The part highlighted in  blue  is not underlined, so  everything else must match up to that phrase using parallel wording or structure ! Now let's take a closer look at the options, and see which ones use parallelism correctly:

(A)  Covering  71 percent of Earth’s surface, the oceans play an essential role in  maintaining  the conditions for human existence on land,  moderating  --> PARALLEL

(B)  Covering  71 percent of Earth’s surface and playing an essential role in  maintaining  the conditions for human existence on land, the oceans  moderate  -->  NOT PARALLEL

(C) The oceans  cover  71 percent of Earth’s surface and play an essential role in  maintaining  conditions for human existence on land, and  by moderating  -->  NOT PARALLEL

(D) The oceans  cover  71 percent of Earth’s surface,  play  an essential role in mandating the conditions for human existence on land, and  moderate  -->  NOT PARALLEL

(E) The oceans cover 71 percent of Earth’s surface,  playing  an essential role in maintaining the conditions for human existence on land, and they  moderate  -->  NOT PARALLEL

There you go - option A is the ONLY option that uses parallelism correctly!  All other options have at least one section that doesn't match the non-underlined portion of the sentence!

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

DmitryFarber · Answer

Yeah, this is a funny problem. On the one hand, we could disregard the intended meaning and simply look at the three -ing words as parallel items. This would get us to A. If we dig a bit deeper, however, that starts to look strange . . .

For instance, the word "in" appears before the list. I can understand how the oceans play an essential role "in maintaining the conditions" and "in moderating temperature," but "in giving pure water back to the atmosphere" doesn't make sense. It would seem that we are saying oceans are just part of this last process, when in fact they are doing it all by themselves!

Additionally, we might notice that the first item is very general (maintaining conditions), while the other two items are specific ways in which the conditions (temperature and humidity) are maintained. It seems that they must be modifying the first item!

At this point, we might be tempted to drop A. That would be unfortunate, because then someone who didn't pay attention to all this would get the problem right, while we would miss it! To me, that is not great design on the GMAT's part--we don't see that kind of thing too often. In any case, if we look down the list using this new interpretation, we still won't find a parallel answer choice. Answer A's only offense seems to be a stray comma. Let's keep it.

Now, why is that comma there? Sometimes we add a comma where it might not seem warranted, with the goal of increasing clarity. Since the phrase "moderating temperature" is itself modified, we might think that "giving" is meant to be parallel with "the absorption." That would make "giving" another way that the oceans modify temperature. The comma makes it clear that "giving" is a new item unto itself.

gmatgrl · Answer

Hello DmitryFarber, thanks for the  phenomenal  analysis. This portion however, is not clear when you say: the phrase "moderating temperature" is itself modified.

Also, when you mention "another way that the oceans modify temperature", I believe you mean to say "another way that the oceans moderate temperature". Please confirm.

DmitryFarber · Answer

Sorry for the belated clarification:

1) the phrase "moderating temperature" is itself modified

"Moderating temperature" is an adverbial modifier. It modifies the previous clause: "the oceans play an essential role . . . " However, we don't just say "moderating temperature" and move on to something else. The phrase "by the absorption of heat and carbon dioxide" modifies the modifier! How do the oceans moderate temperature? By the absorption of heat and carbon dioxide. This additional modifier makes the sentence more complicated, and I think that's why the author added a comma. If the modifying phrase were just "moderating temperature and giving back pure water," there would be absolutely no reason to put a comma between the two modifiers.

2) Also, when you mention "another way that the oceans modify temperature", I believe you mean to say "another way that the oceans moderate temperature".

You're absolutely right. All that moderating and modifying got me a bit mixed up. I've corrected the original post for clarity.

eddy8700 · Answer

Covering 71 percent of Earth’s surface, the oceans play an essential role in maintaining the conditions for human existence on land, moderating temperature by the absorption of heat and carbon dioxide, and giving pure water back to the atmosphere through evaporation

A Covering 71 percent of Earth’s surface, the oceans play an essential role in maintaining the conditions for human existence on land, moderating

B. Covering 71 percent of Earth’s Earth’s surface and playing an essential role in maintaining the conditions for human existence on land, the oceans moderate

C. The oceans cover 71 percent of Earth’s surface and play an essential role in maintaining conditions for human existence on land, and by moderating

D. The oceans cover 71 percent of Earth’s surface, play an essential role in mandating the conditions for human existence on land, and moderate

E. The oceans cover 71 percent of Earth’s surface, playing an essential role in maintaining the conditions for human existence on land, and they moderate

Covering 71 percent of Earth’s surface, correctly modifies the subject here the oceans
Verb-ing modifier,clause
can modify the subject of the clause and the entire clause itself for ex
Wearing the black shirt,John killed the snake.
Here modifier modifies the John i.e subject

In choice C
cover and play two things happening which is not the intended meaning of the sentence
In D and E and B
and moderate is not correct as we have in non underlined part giving

So A is the best answer
moderating || giving

BijayKru · Answer

Covering 71 percent of Earth’s surface, the oceans play an essential role in maintaining the conditions for human existence on land, moderating temperature by the absorption of heat and carbon dioxide, and giving pure water back to the atmosphere through evaporation.

(A) Covering 71 percent of Earth’s surface, the oceans play an essential role in maintaining the conditions for human existence on land, moderating

(In non underline part , and giving  in underline part it should be  , and moderating ):  Correct

(B) Covering 71 percent of Earth’s surface and playing an essential role in maintaining the conditions for human existence on land, the oceans moderate
 (In non underline part , and giving  but underline part it is  , the oceans moderate ) (Wrong)
(C) The oceans cover 71 percent of Earth’s surface and play an essential role in maintaining conditions for human existence on land, and by moderating

(In non underline part , and giving  but underline part it is  , and by moderating ) (Wrong)

(D) The oceans cover 71 percent of Earth’s surface, play an essential role in mandating the conditions for human existence on land, and moderate

(In non underline part , and giving  but underline part it is  , and moderate ) (Wrong)

(E) The oceans cover 71 percent of Earth’s surface, playing an essential role in maintaining the conditions for human existence on land, and they moderate

(In non underline part , and giving  but underline part it is  , and they moderate ) "They??" (Wrong)

daagh · Answer

Covering 71 percent of Earth’s surface, the oceans play an essential role in maintaining the conditions for human existence on land, moderating  temperature by the absorption of heat and carbon dioxide, and giving pure water back to the atmosphere through evaporation

(A) Covering 71 percent of Earth’s surface, the oceans play an essential role in maintaining the conditions for human existence on land, moderating

(B) Covering 71 percent of Earth’s surface and playing an essential role in maintaining the conditions for human existence on land, the oceans moderate

(C) The oceans cover 71 percent of Earth’s surface and play an essential role in maintaining conditions for human existence on land, and by moderating

(D) The oceans cover 71 percent of Earth’s surface, play an essential role in mandating the conditions for human existence on land, and moderate

(E) The oceans cover 71 percent of Earth’s surface, playing an essential role in maintaining the conditions for human existence on land, and they moderate

I couldn’t worry much about the serial comma (,) before the second item of the list in this case, not only because it is in the non-underlined part and but also because we can trump clarity over convention. Without the comma, it might weirdly appear that moderating temperature is achieved by two things, namely, by the absorption of A and B and by giving pure water through evaporation. I think GMAT is correct in inserting the serial comma.
 
Now with our main task, we may see that there is a present participle (giving) in the non-underline part. To match that participle, we need another present participle in the underlined part. Therefore, choices that depict a verb as in B, D, and E are out at the first strike.

In C, the participle moderating is a modifier and cannot be attached to a clause by conjunction. The relevant question is how many ‘ands’ can a sentence have in a list. A is perfectly parallel in that sense.

dabaobao · Answer

Main Issue: 
Parallelism with the non-underlined part: "giving pure water..."

(A) Covering 71 percent of Earth’s surface, the oceans play an essential role in maintaining the conditions for human existence on land, moderating  - Correct

(B) Covering 71 percent of Earth’s surface and playing an essential role in maintaining the conditions for human existence on land,  the oceans moderate   - Wrong: 1) Parallelism 2) Meaning

(C) The oceans cover 71 percent of Earth’s surface and play an essential role in maintaining conditions for human existence on land,  and by moderating   - Wrong: 1) Structure 2) Meaning

(D) The oceans cover 71 percent of Earth’s surface, play an essential role in mandating the conditions for human existence on land,  and moderate   - Wrong: 1) Parallelism 2) Meaning

(E) The oceans cover 71 percent of Earth’s surface, playing an essential role in maintaining the conditions for human existence on land,  and they moderate   - Wrong: 1) Parallelism 2) Meaning

avigutman · Answer

Video solution from Quant Reasoning starts at 00:26:55 Subscribe for more: https://www.youtube.com/QuantReasoning? ... irmation=1 https://www.youtube.com/watch?v=1MmFniFGem4

kadamhari825 · Answer

MY POE

(a) 'covering...surface' is modifying the oceans seems good. the core 'the ocean play an essential role in maintaining the conditions for human existence on land ' followed up by adverbial modifier 'moderating...and giving....' seems fine and making sense too. keep it

(B) 'covering and playing' are modifying the oceans, that's ok, but after the core " the ocean moderate temperature ...carbon dioxide "we do not have anything in sentence to make parallel with " and giving pure...." , so eliminate it

(C) again we have parallelism error. we do not have anything in sentence to make parallel with " and by moderating and giving pure....." so eliminate it
it would have made sense if we did not have 'AND' before moderating

(D) in this option it seems like ocean do list of things but at the end in non underlined part of sentence " giving pure ...." does not have any finite verb to make it parallel with rest of the sentence, eliminate this option also.

(E) in second clause it seems like we have parallelism but here too we do not have any finite verb with " giving pure ..." to make parallel sentence with "they moderate temperature by absorption of heat and carbon dioxide "

correct option A

Varane · Answer

In the second option, what happens when we drop the and?

Covering 71 percent of Earth’s surface and playing an essential role in maintaining the conditions for human existence on land, the oceans moderate  temperature by the absorption of heat and carbon dioxide, giving pure water back to the atmosphere through evaporation.

Please let me know. Will help clear concept.

Posted from my mobile device

ExpertsGlobal5 · Answer

Hello  Varane ,

We hope this finds you well.

To answer your query, if we drop the "and", the sentence would be grammatically correct but lead to an incorrect meaning.

The use of the "comma + present participle ("verb+ing" - "giving" in this sentence)" to modify the verb "moderate" incorrectly implies that the oceans moderate temperature by the absorption of heat and carbon dioxide,and   as a result   give pure water back to the atmosphere through evaporation; the intended meaning is that the oceans play an essential role in maintaining the conditions for human existence on land   because   they perform the   separate and equal actions   of moderating temperature by the absorption of heat and carbon dioxide and giving pure water back to the atmosphere through evaporation; remember, the introduction of present participle ("verb+ing"- “giving” in this case) after comma generally leads to a cause-effect relationship.

In other words, your version of Option B incorrectly conveys that "play" and "give" are two separate and equal actions that are subordinate to the action "moderate", but the intended meaning is that "give" and "moderate" are two separate and equal actions that are subordinate to "play".

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

Anhezjel · Answer

I believe it all boils down to the meaning. If we remove all the additional words, the meaning is just:

1. Oceans cover 70% of Earth
2. Oceans create conditions for human existence by:
 a)moderating temperature
 b)giving pure water back to the atmosphere

The key is relationship between "creating conditions" and "moderating temperature". Only the option A correctly states that the conditions for human existence are created BY moderating temperature and BY giving pure water back to the atmosphere.

ExpertsGlobal5 · Answer

Hello  Anhezjel ,

We hope this finds you well.

To add to your post, here, we would like to mention that your reasoning is correct; kudos.

Option A conveys the intended meaning by modifying the clause "the oceans play an essential role in maintaining the conditions for human existence on land" with the "comma + present participle ("verb+ing" - "moderating" and "giving" in this sentence)" constructions; remember, the introduction of present participle ("verb+ing") after comma generally leads to a cause-effect relationship.

To understand the concept of "Comma Plus Present Participle for Cause-Effect Relationship", you may want to watch the following video (~3 minutes):

https://www.youtube.com/watch?v=AVLneikI70Q

All the best!
Experts' Global Team

VerbalBot · Answer

Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.

Covering 71 percent of Earth's surface, the oceans play an essential

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Sentence Correction (SC - EA only) Questions

Covering 71 percent of Earth's surface, the oceans play an essential

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards