kntombat
AndrewN, Could you provide your take on the question above?
Sure thing,
kntombat. If you strip the sentence of its modifiers and get it down to a barebones level, it is easy to spot the logical continuation:
The yield... is expected to increase... and then to stabilize...There are parallel expectations here that are joined by a comma-less
and (as in,
A and B). To be honest, I checked the rest of the answers for this parallelism in verb conjugation right away.
B. to increase... and then
to stabilizeC. to increase... and then
stabilizingD. to increase... then
stabilizingE. to increase... then
stabilizingIt is not as though there could never be a sentence that employed different conjugations of a verb, but on the GMAT™, if a parallel element exists to something before a comma-less
and, that sentence is strongly preferred. Between (A) and (B), only the latter part differs:
A. which will allow such an extraction rate at least for [50 years' production]
B. an extraction rate that will allow at least [50 years' production]
In terms of meaning, choice (A) is a mess. The
which clause seems to be commenting on the entire sentence up to that point, something better accomplished by the phrase in (B);
such an extraction rate is somewhat confusing, since we have not seen such a rate mentioned explicitly (whereas (B) labels it such); and the split timeline, with words falling between
will allow and
at least, is harder to follow than the alternative presented in (B). In short, there is no compelling reason to steer clear of (B), making it the best answer of the lot. I like to think of these kinds of questions as sub-1-minute questions. Again, if you cannot find a reason to argue against an answer choice, then pick it. (Watch how many questions you start to get right.)
I hope that helps. Thank you for thinking to ask me about this one.
- Andrew