Premise: Kurt Vonnegut is one of America's greatest science-fiction writers. He has written many stores and novels - Slaughterhouse Five is a masterpiece among them.
Paradox: or decades Vonnegut denies writing science fiction however now embraces the act that he is a master of the genre.
Why is it that Vonnegut denied being a science fiction writer or years but now enjoys the living it? The question however asks to identify something which would not explain the paradox or does nothing.
A. early in Vonnegut's career, science fiction was largely considered by critics to be an inferior genre. – WRONG. May be Vonnegut didn’t want to be tagged as an inferior writer.
B. Vonnegut did not want to be pigeonholed as a science-fiction writer. – WRONG. May be Vonnegut didn’t want to remain in boundaries but explore the wide facets of writing.
C. as a young author, Vonnegut's favorite writers were all science-fiction writers. – CORRECT. It might be true that he indeed wrote science-fictions thus he enjoys it now but option does not explain why Vonnegut denied it all earlier.
D. science fiction has become a legitimate literary genre. – WRONG. May be science-fiction earlier wasn’t recognized as legitimate but now it is. So Vonnegut might have thought of not being left out thus denied it for years before accepting it.
E. science fiction has become an increasingly popular genre (for readers and writers alike) because of the increased importance of science and technology in our lives. – WRONG. ‘increasingly popular’ suggests that science-fiction was not that much popular earlier which might have led Vonnegut to deny it for decades.
IMO Answer (C).