【单选题】

It may be inferred from the passage that, in contrast to their present view, microbiologists once believed that
A．(A) only a single feature of endospore biology was responsible for their success

B．(B) potentially, a canning process could be developed that was capable of destroying all endospores
C．(C) ultraviolet radiation was a possible means of destroying microorganisms that practice cellular dormancy
D．(D) cellular mitosis was the root cause of the resilience of the microorganisms under discussion
E．(E) only single-celled organisms, like those of fungal spores, could practice cellular dormancy