culsivaji wrote:
The prairie vole, a small North American grassland rodent, breeds year around, and a group of voles living togather consists primarily of an extended family, often including two or more litters. Voles commonly live in large groups from late autumn to winter; from spring thru early autumn, however, most voles live in far smaller groups. The seasonal variation in groups 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 above?
A) It is the spring and in the early summer that prairie vole communities generally contain the highest proportion of young voles. -->This doesn't support or provides any explanation as why there is seasonal variations due to mortality.
B) Prairie vole populations vary dramatically in size from year to year. --> This doesn't strengthen at all. It says that by default the population varies and as such there are no seasonal variation factors.
C) The prairie vole subsists primarily on broad-leaved plants that are abundant only in spring. --> okay plants are abundant in spring. But we don't have any information if due to scarcity are the rodents dying ? no information given.
D) Winters in prairie vole's habitat are often harsh, with temperatures that drop well below freezing.-->Okay temperatures drop in winter, but no information given to conclude whether due to low temperature are they dying ?
E) Snakes, a major predator of young prairie voles, or active only from spring thru early autumn. --> Perfect ! This option explains why the rodents are dying in different different seasons because of snakes which are active in certain period and predate on the rodents !
Can someone please explain to me meaning of this line "The seasonal variation in groups size can probably be explained by a seasonal variation in mortality among young voles" , doesn't this mean , rodents are dying because of seasonal changes , which is supported by choice D. Please help me understand how E is correct. Would really appreciate your help.
Thanks
Megha