Extinction is a process that can depend on a variety of ecological, geographical, and physiological variables. These variables affect different species of organisms in different ways, and should, therefore, yield a random pattern of extinction. However, the fossil record shows that extinction occurs in a surprisingly definite pattern, with many species vanishing at the same time.
Which of the following, if true, forms the best basis for at lest a partial explanation of the patterned extinction revealed by the fossil record ？（）
A.Major episodes of extinction can result from widespread environmental disturbances that affect numerous different species.
B.Certain extinction episodes selectively affect organisms with particular sets of characteristics unique to their species.
C.Some species become extinct because of accumulated gradual changes in their local environments.
D.In geologically recent times, for which there is no fossil record, human intervention has changed the pattern of extinction.
E.Species that are widely dispersed are the least likely to become extinct.
