Question ID:PT55 S1 Q20  Passage:A study of rabbits in the 1940s convinced many biologists that parthenogenesis‚ reproduction without fertilization of an egg‚ sometimes occurs in mammals. However, the study's methods have since been shown to be flawed, and no other studies have succeeded in demonstrating mammalian parthenogenesis. Thus, since parthenogenesis is known to occur in a wide variety of nonmammalian vertebrates, there must be something about mammalian chromosomes that precludes the possibility of parthenogenesis. Stem:A flaw in the reasoning of the argument is that the argument Correct Answer Choice:AChoice A:takes for granted that something that has not been proven to be true is for that reason shown to be false Choice B:infers that a characteristic is shared by all nonmammalian vertebrate species merely because it is shared by some nonmammalian vertebrate species Choice C:rules out an explanation of a phenomenon merely on the grounds that there is another explanation that can account for the phenomenon Choice D:confuses a necessary condition for parthenogenesis with a sufficient condition for it Choice E:assumes that the methods used in a study of one mammalian species were flawed merely because the study's findings cannot be generalized to all other mammalian species