求助perp-1-3

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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.

请牛牛指点一下，为什么选E呢，偶选的b.

原文－ large 从深秋到冬天 and smaller 从春天到早秋, 得出结论The seasonal variation in group size can probably be explained by a seasonal variation in mortality among young voles.   问支持

ABCD读一遍即可排除，强调的时间不对。B单看from year to year就错了，应该是季节变化。再看意思完全与上面结论无关。

E的时间状语完全吻合，其次含义，由于young voles的主要捕食者－蛇仅在这段时间活动，也就是young voles被吃得比较多，自然数量下降。only－正好表明其他时间，蛇的威胁就没有了，young voles自然数量会多一些。