Question ID:PT91 S2 Q21 Passage:Professor:  Many scientists hypothesize that there is an invisible "light-absorbing medium" in outer space. In support, they argue that the medium's existence would explain the low visibility of other star systems from Earth. But there is actually no reason to believe that the hypothesis is correct, since the low visibility in question is already completely explained by the general theory of relativity.  Stem:Which one of the following is an assumption required by the professor's argument?  Correct Answer Choice:EChoice A:The low visibility of other star systems from Earth would not be adequately explained by the existence of an invisible light-absorbing medium in outer space, even if there were such a medium.  Choice B:The hypothesis of an invisible light-absorbing medium in outer space is correct only if it adequately explains the low visibility of other star systems from Earth. Choice C:A hypothesis is likely to be correct if there is some phenomenon that it adequately accounts for and that is not adequately accounted for by an existing theory. Choice D:Most scientists who posit the invisible light-absorbing medium accept the general theory of relativity. Choice E:The general theory of relativity does not depend upon the hypothesis that there exists an invisible light-absorbing medium in outer space.