Other than the main topic of Zora Hurston's book, there is also an underlying theme indicating that the perspectives of the critic has changed from, mainly voicing their protest agains racism, to opening up to other facets of everyday black life. One of these facets was the voice of a black woman in everyday life.
For 1. C fits the underlying theme, which says that an opinion by a critic is a function of the current perspective of what voice of the black people should be. At the time (1937) all black critics were interested in voicing their protest against racism and that is what they thought was the black voice.
The perspective of recent critics has change to a multi-faceted perspective which opens them up to accept other types of literature related to black life.
For 2. B the passage does say that the book became obscure as early critics looked at the book from a narrow perpspective.
[quote="laxieqv"]Many literary scholars believe that Zora Neale Hurston’s Their Eyes Were Watching God (1937) has been the primary influence on some of the most accomplished Black women writing in the United States today. Indeed, Alice Walker, the author of the prize-winning novel The Color Purple, has said of Their Eyes, “There is no book more important to me than this one.â€