【单选题】

The author's primary purpose in the passage is to
A．(A) describe the limits of biologists' understanding of the phenomenon of cellular dormancy

B．(B) explain how certain organisms have adapted to withstand environmental adversity
C．(C) contrast the survival techniques of two organisms which use dormancy to survive hostile environments
D．(D) explain why endospores are so adept at surviving the traditional canning process
E．(E) suggest which methods are effective for killing endospores at which are not