Hi, if we look at the sentence in question where the author tells us that the environment was in flux at the time, the second half of the sentence tells us that in this environment art had to be many things to many people. This explains the success of the cakewalk as in D.
There just isn't support for E. The author mentions the flux to support what was said in the second half of that sentence at the end of paragraph three. Moreover, the author never tells us that white parodies actually ever reached a wide audiences.