The primary purpose of the second paragraph is to

A contrast Kelley's viewpoint on the Popular Front with that of previous historians

B defend the Popular Front from Kelley's attacks on it

C question the political usefulness of searching for common ground between radicals and liberals

D enumerate the differences between the Popular Front and the Third Period

E argue that one valid way to approach the study of communism in the United States is to discuss its impact on African-American workers