2. 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 not able to imagine, even less to remember, what segregation was like.
(B) so profound that many young Americans cannot imagine, much less remember
2. 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 not able to imagine, even less to remember, what segregation was like.
(B) (which is )so profound that many young Americans cannot imagine, much less remember