Hello Everyone!
Let's tackle this question, one problem at a time, and narrow it down to the right answer quickly! To start, let's take a closer look at the original question and highlight any major differences between the options in orange:
Australian embryologists have found evidence that suggests that the elephant is descended from an aquatic animal, and its trunk originally evolving as a kind of snorkel.
(A) that suggests that the elephant is descended from an aquatic animal, and its trunk originally evolving
(B) that has suggested the elephant descended from an aquatic animal, its trunk originally evolving
(C) suggesting that the elephant had descended from an aquatic animal with its trunk originally evolved
(D) to suggest that the elephant had descended from an aquatic animal and its trunk originally evolved
(E) to suggest that the elephant is descended from an aquatic animal and that its trunk originally evolved
After a quick glance over the options, we see a few major differences we can focus on:
1. that suggests that / that has suggested / suggesting that / to suggest that (Meaning)
2. is descended / descended / had descended (Verb Tense & Meaning)
3. how each option ends (Punctuation, Conjunctions, Parallelism)
Let's start with #1 on our list. While it may seem like these phrases could be interchangeable, they do mean slightly different things. What we're looking for here is a sentence that states the embryologists are the ones who suggested that elephants descended from aquatic animals. We need to rule out any options that change or confuse this meaning.
(A) Australian embryologists have found evidence that suggests that the elephant is descended from an aquatic animal, and its trunk originally evolving
This is INCORRECT because it's not conveying the meaning we want. This sentence says that the embryologists found evidence that already suggests that elephants descended from aquatic animals. We're looking for a sentence that conveys that the embryologists found evidence and then made the suggestion themselves!
(B) Australian embryologists have found evidence that has suggested the elephant descended from an aquatic animal, its trunk originally evolving
Again, this is INCORRECT because it's not conveying the meaning we're looking for. The embryologists are the ones who made the suggestion, not the evidence they found!
(C) Australian embryologists have found evidence suggesting that the elephant had descended from an aquatic animal with its trunk originally evolved
Again, another one that tells us the evidence made the suggestion, and not the embryologists. So this is also INCORRECT.
(D) Australian embryologists have found evidence to suggest that the elephant had descended from an aquatic animal and its trunk originally evolved
This is OKAY for now. It's clear that the embryologists found the evidence, and then they used that evidence to make their own suggestion. So let's keep this one for now!
(E) Australian embryologists have found evidence to suggest that the elephant is descended from an aquatic animal and that its trunk originally evolved
This is OKAY for now. It's clear that the embryologists found the evidence, and then they used that evidence to make their own suggestions. So let's keep this one for now!
We can eliminate options A, B, & C because they change or distort the intended meaning.
Now that we only have 2 options left, let's take a closer look at #2 & #3 on our list to determine which option is the better choice:
(D) to suggest that the elephant had descended from an aquatic animal and its trunk originally evolved
This options is INCORRECT for a couple reasons. First, the past perfect "had descended" doesn't work here. Past perfect should be used to indicate that you're talking about two past tense events, and that the one in past perfect tense happened first. We know that elephants were descended from aquatic animals in the past, but they still are today, so this verb tense doesn't make sense here. Second, it doesn't use parallel structure to discuss the two suggestions:
to suggest that the elephant had descended from an aquatic animal and its trunk originally evolved --> to suggest that X and Y = NOT PARALLEL
It would need to include the word "that" on both items, or eliminate it from both items to be parallel.
(E) to suggest that the elephant is descended from an aquatic animal and that its trunk originally evolved
This is CORRECT! It uses parallel structure to word the two suggestions (that the elephant / that its trunk), and the present progressive verb tense makes more sense to indicate that elephants were descendants of aquatic animals in the past, and they still are today!
There you have it - option E is the correct choice!
Don't study for the GMAT. Train for it.