Covering 71 percent of Earth’s surface

boomgoesthegmat wrote: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 maintaining 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

A

If you read the given sentence carefully you will see that after the final comma there is an AND followed by a present participle, GIVING. Since AND must connect what follows it to something previous, the correct answer, in order to be parallel, MUST contain another present participle. This is what you already have in option A: MODERATING TEMPERATURE ..., AND GIVING PURE WATER BACK. This is the only option that contains this construction, and A is therefore the only possible correct answer.

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Experts:

Choice A might be an OA but it sounds quite awkward to me. Here is why -

It seems to me that the intent of the author is to say "Covering 71 percent of Earth’s surface, the oceans play an essential role in maintaining the conditions for human existence on land, BY moderating temperature by the absorption of heat and carbon dioxide, and BY giving pure water back to the atmosphere through evaporation" i.e. the oceans play an essential role ...BY moderating temperature ....and BY giving pure water.
However, I am not quite sure if I see very often that a participle phrase especially when it occurs at the end of the sentence is used instead of using BY construction. For instance -
Sweeping across the night sky, the bats hunted their prey (sounds quite ok to my ear)
The bats hunted their prey, sweeping across the night sky (sounds awkward)
Second kind of construction is not very common at least for me.

Does it make sense? What Im missing here in terms of GMAT preference?

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 purple 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!


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