Why did the author conclude the article by explaining W. E.B. DuBois' analysis of black progress during Reconstruction? (A) to make a connection between past and current efforts to diminish the political power of black Americans
(B) to illustrate how much progress black Americans made despite white obstruction and intimidation
(C) to establish the importance of DuBois' influence on black history and political thought
(D) to describe why Reconstruction eventually collapsed, enabling the rise of the Jim Crow era