MGMAT5:

The coloration of insects can serve as camouflage, as in the case of green insects that spend their lives in or near foliage, or to warn predators, as in the case of insects colored in yellow and black, which often signals that it is poisonous.

A. or to warn predators, as in the case of insects colored in yellow and black, which often signals that it is poisonous.
B. or for warning predators, as in the case of insects that have yellow and black coloring, which often signals that it is poisonous.
C. or as a warning to predators, as in the case of insects bearing a combination of yellow and black, which often signals that they are poisonous.
D. or as a predator's warning, as in the case of insects that are colored yellow and black, which often signals that they are poisonous.
E. or to warn predators, as in the case of yellow-and-black insects, which often signals that they are poisonous.

The below construction looks right to me (E):
The coloration of insects can serve as comouflage
The coloration of insects can serve to warn predators

However the explanation suggests the following (C):
The coloration of insects can serve as camouflage
The coloration of insects as a warning to predators

Any help?

Pretty straightforward - serve as X or serve as Y is parallel

OR

serve to X or serve to Y is parallel

How can serve as X or serve to Y be parallel? On one hand you are saying serve 'as' and on the other hand you are saying serve 'to'; not parallel by any stretch.

On a different note I think all the options incorrectly use 'which' to refer to 'black' or 'black coloring' both of which are incorrect!

sarfrazyusuf is right as usual! :)

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Tim Sanders
Manhattan GMAT Instructor

The test answer says for option D => It also incorrectly uses "which", which should refer only to the previous noun, not to an entire action or clause.However we have the same format for "which " for some of the other choices including the OA C ..so how does "which" refer correctly to the preceeding noun in c but not in some of the other choices

sidd, this thread may help you: the-which-rule-t7033.html

Read that, and then look carefully at the difference between C and D in regards to the use of "which".

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Jamie Nelson
ManhattanGMAT Instructor

I dont know how helpful I will be. But, sometimes rotating the order helps.

For eg: The coloration of insects can serve as a warning - looks correct.

Good tip! That is a good strategy to check parallelism.

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Jamie Nelson
ManhattanGMAT Instructor