OFFICIAL EXPLANATION



THE PROMPT

• Note: when an animal is mentioned and its number is not clear, GMAC will give us a clue.
"Zooplankton" is plural. In the non-underlined portion of the sentence, zooplankton are described as marine animals.
Plurality doesn't matter in this question, but it does in many questions involving animals.

• Strip this sentence. Result:
Zooplankton sink from the water's surface when the sun rises to escape predators, ascending again to feed at night.

THE OPTIONS


• the sun does not rise [in order] to escape predators
-- to escape predators explains why zooplankton sink from the water's surface.
Those two phrases should be next to each other.

• Nothing is wrong with ascending.
-- ascending is an elegant way to make a dull sentence change rhythm.
• Ascending again to feed at night is a logical result of the preceding clause.
-- in order to escape predators, zooplankton sink at sunrise.
-- Well, if predators arrive at sunrise, apparently the danger has something to do with light and visibility.
When it gets dark, the zooplankton ascend to eat.
-- although I really like the creativity of the argument, ascending is not ambiguous.
We know that ascending refers to zooplankton. The sun does not eat.


• in English, when we talk about dawn, we say when the sun rises or at sunrise.
-- The sun's rise is not idiomatic.
• I say more below about the possessive case. The water's surface, after all, appears in the correct answer.
• Back to back infinitives? The repetition in to escape predators, to ascend is awkward

• Put C in the stripped sentence:
Zooplankton and sink from the water's surface when the sun rises, escaping predators and ascending again to feed at night.
-- That AND should be a verb. This sentence is nonsensical.

• everything looks good


• at the sun's rising is not idiomatic. If in doubt, compare to D.
-- By the time you take the GMAT, you should have read in English enough to know immediately whether (D) or (E) is better.
Try The Harvard Magazine. You can find it for free HERE
It contains short and long passage (RC, anyone?), fascinating topics, and good writing.

The correct answer is D.


OTHER ISSUES

• Possessive nouns: the sun's rise and the sun's rising
-- Xylan , I would have to mine data before I signed onto what you say is a guideline. What is the source of this guideline?
You seem to be a very thorough student of language. You certainly are conscientious.

I am not saying that the guideline is incorrect. I haven't read official questions with that issue in mind.
How possessive nouns behave is complicated and not something that is easily articulated in part because some inanimate nouns take possessives and others do not, but the difference can turn on many bases. One basis is idiom. Another is words used. (Water's surface = concrete noun, concrete noun whereas the sun's rise = concrete noun, action noun.)
Why is the water's surface okay?
I would love to know the source. (I have heard this rule mentioned once before. From my review of official questions, I found a pattern in which inanimate objects in the possessive case that do not fit my guideline below frequently are not in the correct answer. My sense of those words, though, was that the "of X" construction in other options was much easier to follow. In other words, the issue is one of style.)

We have to be a little careful with these guidelines. I pulled three official questions quickly. All use possessive inanimate objects.
• the company's - the question is HERE
• the nation's - the question is HERE
• the planet's - the question is HERE

• the rule about possessives
-- There is a rule that I have never seen GMAC violate.

Do not use both OF and ['s] in the same possessive construction.
-- GMAC considers such use redundant. Many style guides do not. Ignore them.

Sasha and Artem are cousins.

Correct: I'm going to the cafe to meet Sasha, a cousin of Artem.
Correct: I'm going to the cafe to meet Sasha, Artem's cousin.
Wrong: I'm going to the cafe to meet Sasha, a cousin of Artem's.

• a guideline - avoid plural possessives (nouns that end in "S" and are followed by an apostrophe (--s')
Examples: animals' characteristics (characteristics of animals); humans' diseases (diseases in humans)
About 3/4 of the time—some sources say as often as 90% of the time—these forms are wrong.

COMMENTS
Manjugupta and Juliiiii , welcome to SC Butler.

As always, I am glad to see posts by many people.
The analysis in these posts is good. Explanations that exist range from good to excellent.
In order to qualify for kudos, you must explain your answers.

Meaning :-
Sentence intends to convey the activity of a margine organism during warmer months.
Zooplankaton do 1 sink to escape predators when sun rises and 2 ascend to feed at night.

The meaning can be best conveyed by showing the both actions using AND.

Error Analysis:-
During warmer months, zooplankton,
microscopic marine animals that drift in oceans and bodies of fresh water,
sink from the water's surface when the sun rises to escape predators, ascending again to feed at night.

1. The sentence is structured as the sun rises to escape by ascending again night
2. to escape predators should modify the verb sink.
3. and is missing before ascend.


A) sink from the water's surface when the sun rises to escape predators, ascending
As mentioned above
B) sink from the water's surface at the sun's rise to escape predators, to ascend
to ascend - phrase modifying sink - illogical,

C) and sink from the water's surface when the sun rises, escaping predators and ascending
and - wrong , No verb for Zooplan, escaping modifiies sun rises
D) sink from the water's surface in order to escape predators when the sun rises and ascend
Conveys the meaning.

E) sink from the water's surface to escape predators at the sun's rising, and ascend
at the sun's rising is awkward.


So i believe D is the right option.

A) sink from the water's surface when the sun rises to escape predators, ascending
The use of "ascending" is making illogical relationship between the two action.

B) sink from the water's surface at the sun's rise to escape predators, to ascend
Same as above, the "sink" doesn't lead to the "ascend."

C) and sink from the water's surface when the sun rises, escaping predators and ascending
There is no parallel action in the preceding sentence before "and."

D) sink from the water's surface in order to escape predators when the sun rises and ascend
CORRECT

E) sink from the water's surface to escape predators at the sun's rising, and ascend
"at the sun's rising" has different meaning from the original sentence.

A) sink from the water's surface when the sun rises to escape predators, ascending : Incorrect,

B) sink from the water's surface at the sun's rise to escape predators, to ascend : Incorrect, awkward construction. Now, the sentence means that zooplankton sink ...to escape, to ascend.

C) and sink from the water's surface when the sun rises, escaping predators and ascending : incorrect, Sink is one of the two verbs and an 'and' should not be used before it.

D) sink from the water's surface in order to escape predators when the sun rises and ascend : Sink is made parallel to ascend, Correct.

E) sink from the water's surface to escape predators at the sun's rising, and ascend : awkward construction. at sun rise should have been correct usage.
_________________

IMO correct answer is D

Xylan, thanks for the information regarding possessiveness of inanimate things. This is wrong. I get to know the new information. I was discarding this split on account of awkwardness in sentence structure.

During warmer months, zooplankton, microscopic marine animals that drift in oceans and bodies of fresh water, sink from the water's surface when the sun rises to escape predators, ascending again to feed at night.

A) sink from the water's surface when the sun rises to escape predators, ascending - Issue with parallelism, "Drift" plural verb, goes well with sink, but "ascending" is not a proper usage - Incorrect

B) sink from the water's surface at the sun's rise to escape predators, to ascend - "to ascend" is incorrect again for the reason mentioned above.

C) and sink from the water's surface when the sun rises, escaping predators and ascending - "escaping predators and ascending" tried to make this parallel, but these activities are not taking place simultaneously & hence verb+ing modifier cannot properly modify the clause preceding it.

D) sink from the water's surface in order to escape predators when the sun rises and ascend - Correct

E) sink from the water's surface to escape predators at the sun's rising, and ascend - possessiveness about the inanimate object as i mentioned above, also "," before and is making it incorrect.

Glad you found the notion useful!

Just to give a heads-up to the people on the GMAT-forum (Notice, how it's people on the GMAT-forum NOT the GMAT-forum's people ) -

The engine of the car is preferred to the car's engine. - It's a preference, NOT a rule.

However, the F1 car of Michael Schumacher is almost similar to Michael Schumacher's F1 car.
Thus, the rule - The possessiveness of inanimate things is wrong.

I have posted the official explanation HERE

generis

I must consider myself lucky to get to OA in spite of incorrect approach.
I thought coma_verb-ing (ascending) did not make sense with preceding clause
(the sun rises to escape predators). Could you clarify how it jumped over this phrase
to modify subject of earlier clause: Zooplankton sink from the water's surface.
Is this observed a lot in official questions too?


True, is this similar to searching for an antecedent for a pronoun when we have more than two antecedents?
Can I formulate this rule to search for an unique subject that coma+verb-ing modifies?

I got to OA purely based on ||ism since I thought Zooplankton need two parallel verbs:
sink and ascend (also coma+ and correctly separated two verbs)

Missed out on placement of infinitive - to escape predators - because of my hurried reading
_________________