(A) and burning with resentment against his "oppressors," (B)/ Beginning with the assumption that the negro (C)/ they attempted to bridge the gap of centuries in a generation. (D) whites who held themselves apart were enemies to the blacks (E)/ was equal or superior to the white in natural endowment

On carefully reading the fragments we see that the sentence is about the negro’s attempt to bridge the gap between the whites. B introduces the context of the sentence and it should be the opening part. E further states what the assumption is. Hence, E should follow B. A further continues what is mentioned in E. Thus, A should come next. C concludes the sentence by mentioning that they tried to bridge the gap of centuries. BEAC forms a coherent sentence. Sentence D is out of context.