Dear AjiteshArun,

Thank you for your response. If that's the case, then does that mean in general, it's ok to construct a parallel structure that has two clauses in two different tenses? Thanks!

"and" is difficult word on gmat. "and" show that two entities are parallel grammatically. but for the sentence to be correct, we have to prove that two ideas presented by the two entities are parallel logically. this job is not easy. we have to understand meaning to realize two ideas are parallel. this is focus of gmat test.

without "that " , "and its trunk involved" is parallel grammatically with "scientists have found evidence". but these two ideas can not be parallel logically. instead , "its truck involved" should be parallel with "elephant is decended".

for me, non native, remember the difference between 'be descended' and "descend' is impossible .

snigdha wrote


First thing is that what you assume as ICs are not ICs indeed. You seem to have ignored the subordinate conjunction 'that in front of both the clauses. You know well that when you place a subordinate conjunction in front of an IC, it becomes a DC. In fact, what you have on either side of the parallel marker 'and' are only two DCs.
A comma before 'and' is not the prerogative of an IC. Even in a list that contains more than two items,one uses comma plus 'and' even though the items of the list may not be ICs. Eg -Tom, Dick, and Harry - here we have three nouns but a comma plus and.
Similarly when there are two short ICs joined by a conjunction, we may not use a comma before 'and'
I went to the US last Monday and Trump went to Iceland on the same day. In this case, even though what follows and is an IC, still we do not use the comma.

The structure of a sentence is a primary prerequisite and the foundation of SC.
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Notwithstanding the verb tense issues
What helped me see the answer more clearly before I pulled the trigger is realising that the evidence led the scientists to discover two distinct things:
1. Elephant descended from WA
2. Trunk originally evolved as X
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I think the most important thing to remember here is parallelism. Evidence suggests 2 things and E clearly defines the 2 things by having that in parallel

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100% agreement with the incomparable daagh here. Neither construction ("to suggest" or "that suggests") gives us a clear indication of what the person/people who found the evidence knew or believed prior to finding the evidence, so I wouldn't use that as a decision point at all (for more on that point, check out this post).

Choice (A) has a parallelism issue, so we can rule it out without worrying about "to suggest" vs "that suggests." And that's pretty typical of the GMAT: you might see a choice between two different constructions, but that's doesn't mean that one is right and the other is wrong. Sometimes, both are acceptable, and you'll want to look for other things.

I hope this helps!
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