Quote:
Scientists claim that the discovery of the first authenticated mammal bones in amber could provide important clues of determining, in addition to how, when mammals colonized the islands of the West Indies.
(A) of determining, in addition to how, when mammals colonized the islands of the West Indies
(B) in the determination of how and when the islands of the West Indies were colonized by mammals
(C) to determine how mammals colonized the islands of the West Indies and when they did
(D) for determining when the islands of the West Indies were colonized by mammals and how they were
(E) for determining how and when mammals colonized the islands of the West Indies
OA = E
guptakashish02 wrote:
Quote:
(C) to determine how mammals colonized the islands of the West Indies and when they did
I think there is no problem with "they" as according to parallelism , "they" must refer to mammals only and "to determine" is referring to the purpose for doing.
Just to be clear: the meaning of "they" has nothing to do with parallelism here. "They" is just a pronoun, and it needs to refer back logically to a plural noun of some sort.
I suppose we could argue that there's some potential for ambiguity here, since "they" could refer back to "mammals" or "islands" or "West Indies." But I fundamentally agree with you: it really isn't remotely confusing, and it's obvious enough that "they" refers logically to mammals. (And for anybody who's wondering: pronoun ambiguity can be a problem, but it isn't an absolute rule on the GMAT. More on that in
this video.)
So why is (C) wrong? Hang on, let me answer your question about (E) first, and then we'll compare the two.
guptakashish02 wrote:
Quote:
(E) for determining how and when mammals colonized the islands of the West Indies
Is there ellipsis here like :
for determining how (mammals colonized the islands of the West Indies) and when mammals colonized the islands of the West Indies .
Is it right to have ellipsis before it has been stated in a sentence.
"Ellipsis" is just a jargon-y way of saying that a few words have been omitted from a sentence because they're strongly implied, and really don't need to be included. Honestly, there are no absolute rules that dictate when it's OK to omit words, and when it isn't. The not-very-satisfying truth: if omitting a few words causes confusion, that's a problem. If omitting a few words doesn't make the sentence unclear or confusing, there's no problem. Of course, there's no rule that says when a sentence becomes "unclear" or "confusing" -- those things are, unfortunately, at least a little bit subjective.
But yes, it's fine to have ellipsis before the omitted words have actually been stated. In a sense, this is no different than when a pair of adjectives precedes a noun: in the phrase "green and red M&M's", for example, you wouldn't be tempted to write "green M&M's and red M&M's", right? It's abundantly clear that "green" describes the "M&M's", even though that (tasty) word doesn't appear until later in the sentence.
(And no, this post was not sponsored by any candy companies. But if you happen to run a food company, I can get you some killer product placement in GMAT lessons, in exchange for something tasty...)
OK, on to the real question: why (E) and not (C)?
Quote:
Scientists claim that the discovery of the first authenticated mammal bones in amber could provide important clues of determining, in addition to how, when mammals colonized the islands of the West Indies.
(C) to determine how mammals colonized the islands of the West Indies and when they did
(E) for determining how and when mammals colonized the islands of the West Indies
For starters, "for determining" is the correct idiom here, not "to determine." And that's wildly unsatisfying, as are most of the 25,000 or so idioms in English.
So that's admittedly not something that's likely to help you on the next question.
But notice the waste of words in (C). (E) is perfectly clear and parallel, right? Scientists are collecting clues for determining two things:
how and
when mammals colonized the West Indies. There's nothing WRONG with (C), exactly, but it's much nicer to have the two parallel elements -- "how" and "when" -- right next to each other, in a more succinct statement.
I hope this helps!