CR PREP 1 : 3 怎么理解

sunflower82

The prairie
            vole, a small North American grassland rodent, breeds year-round, and a group of voles living together consists primarily of an extended family, often including two or more litters.  Voles commonly live in large groups from late autumn through winter; from spring through early autumn, however, most voles live in far smaller groups.  The seasonal variation in group size can probably be explained by a seasonal variation in mortality among young voles.

 

Which of the following, if true, provides the strongest support for the explanation offered?

 

(A) It is in the spring and early summer that prairie vole communities generally contain the highest proportion of young voles.

(B) Prairie vole populations vary dramatically in size from year to year.

(C) The prairie vole subsists primarily on broad-leaved plants that are abundant only in spring.

(D) Winters in the prairie voles' habitat are often harsh, with temperatures that drop well below freezing.

(E) Snakes, a major predator of young prairie voles, are active only from spring through early autumn

答案是E，整不明白，为什么不是A。这个蛇的捕食跟vole的smaller groups又关系吗？谢谢！

jian880821

当然是E啦，predator of young prairie voles,意思是vole的捕食者，是吃vole的蛇。你想，春秋季蛇一多，就要吃vole了，vole就少了呗！

A说the highest proportion of young voles，与题干无关吧，无法加强……