Sentence Correction

In some species of cricket, the number of chirps per minute used by the male for attracting females rise and fall in accordance with the surrounding temperature, and they can in fact serve as an approximate thermometer.

(A) for attracting females rise and fall in accordance with the surrounding temperature, and they can in fact serve
(B) for attracting females rises and falls in accordance with the surrounding temperature, which can in fact serve
(C) in attracting females rise and fall in accordance with the surrounding temperature, in fact possibly serving
(D) to attract females rises and falls in accordance with the surrounding temperature, and it can in fact serve
(E) to attract females rises and falls in accordance with the surrounding temperature, in fact possibly serving

OA D

why not E?

If "it" in D refers to "the number", "in fact possibly serving" in E can also refer to "the number" unambiguously while D does so ambiguously("it" in D is somehow ambiguous, but ambiguity is welcomed on GMAT to some level);

Between D and E it comes to a question of certainty and for these types of question it is better to preserve the original meaning

possibly - introduces uncertainty, it may or may serve as thermometer while in D it can serve as a thermometer though the 'it' seems ambiguous the meaning is clear in D.

(D)

(E) is wrong because of "possibly serving"

hoji wrote:In some species of cricket, the number of chirps per minute used by the male for attracting females rise and fall in accordance with the surrounding temperature, and they can in fact serve as an approximate thermometer.

(A) for attracting females rise and fall in accordance with the surrounding temperature, and they can in fact serve
(B) for attracting females rises and falls in accordance with the surrounding temperature, which can in fact serve
(C) in attracting females rise and fall in accordance with the surrounding temperature, in fact possibly serving
(D) to attract females rises and falls in accordance with the surrounding temperature, and it can in fact serve
(E) to attract females rises and falls in accordance with the surrounding temperature, in fact possibly serving

OA D

why not E?

If "it" in D refers to "the number", "in fact possibly serving" in E can also refer to "the number" unambiguously while D does so ambiguously("it" in D is somehow ambiguous, but ambiguity is welcomed on GMAT to some level);

In A and C, rise (plural) does not agree with the number (singular). Eliminate A and C.

In B, which seems to refer to temperature, but it makes no sense to say that the temperature can serve as an approximate thermometer. The intended meaning is that THE NUMBER OF CHIRPS can serve as an approximate thermometer. Eliminate B.

In E, in fact possibly is a contradiction in terms. Something cannot both IN FACT be true and POSSIBLY be true at the same time. Eliminate E.

The correct answer is D.

Here the subject is "the number of chirps"

So (D) is the only choice