Sentence Correction

Roy Wilkins was among the last of a generation of civil rights activists who led the nation through decades of change so profound many young Americans are no ... o remember, what segregation was like.
(A) so profound many young Americans are not able to imagine, even less to remember
(B) so profound that many young Americans cannot imagine, much less remember
(C) so profound many young Americans cannot imagine nor even less remember
(D) of such profundity many young Americans cannot imagine, even less can they remember
(E) of such profundity that many young Americans are not able to imagine, much less to remember

pls give explanation for eliminatig the choices

IMO B

what segregatoin was like indicates past tense. Present should be rejected.

A) so profound many young Americans are not able to imagine, even less to remember
(B) so profound that many young Americans cannot imagine, much less remember
(C) so profound many young Americans cannot imagine nor even less remember
(D) of such profundity many young Americans cannot imagine, even less can they remember
(E) of such profundity that many young Americans are not able to imagine, much less to remember

IMO -- B

What is the correct answer