prep SC part1 96

96.   (29707-!-item-!-188;#058&003977)
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

还是it的指代问题 如果指代number, 那么就是the number.....,and the number...

我们平时说 it helps me and encourages her.  而不说It helps me ,and it encourages her.

这个地方既然两个分句都是一样的主语 为什么要重复呢？

求助