Roy Wilkins was among the last of a generation of civil rights activis

+1 for (B) , So X that Y is correct idiomatic usage...

In A and C, “that” is missing after “profound”. “So + adjective + that..” is the correct idiom.
In D, “that” is missing after “profundity”.
In E, “not able to” and “less to” unnecessarily make the choice wordy.
B follows the idiomatic structure “So + adjective + that…”. Hence, B is the correct answer.

(A) so profound many young Americans are not able to imagine, even less to remember ---> so profound intensifies young americans instead of the change, correct idiomatic usage is so X that Y and even less to remember is awkward

(B) so profound that many young Americans cannot imagine, much less remember ---> so profound correctly modifies change, use of that rectifies idiom error, much less correctly addressed t many young americans

(C) so profound many young Americans cannot imagine nor even less remember ---> Multiple Idiom error 1) So X that Y 2) neither, nor

(D) of such profundity many young Americans cannot imagine, even less can they remember ---> awkward construction

(E) of such profundity that many young Americans are not able to imagine, much less to remember ---> Are not able is to incorrect usage

TIME magazine - September 21, 1981 | Vol. 118 No. 12 (LINK)

When he died last week in New York City at 80, Wilkins had been out of the public eye since his retirement from the N.A.A.C.P. in 1977. Overcome in his last years by age and ill health, he nonetheless remained a revered figure among blacks and whites alike. Wilkins was a gentleman—patient, diplomatic, someone who considered it important to win friends for his cause. He believed, as ardently as any right-wing patriot, that America was a land of opportunity and justice that could, if one worked within the system, be opened to all. His tools were education, court appeals, lobbying and grass-roots organizing; his strength was a rare combination of persuasion and toughness. He was among the last of a generation of civil rights leaders who pulled and tugged and cajoled the nation through decades of change so profound that many young Americans cannot imagine, still less remember, what segregation was like.

Official Explanation :

Choice A can be faulted for omitting that after profound; the idiomatic form of the expression is ''so X that Y." Also, much less remember is more idiomatic than even less to remember, and cannot imagine is more concise than are not able to imagine.

Choice B is best.

Choice C lacks that after profound, and nor is incorrectly used to join verbs modified by cannot.

In choice D, of such profundity is wordy, that is missing, and even less can they remember is not an idiomatic way to complete cannot imagine.

In choice E, of such profundity and, are not able to imagine are wordy, and the to in to remember is unnecessary.

What does "still less remember" signify/mean?

Daagh, GMatNinja please throw some light on this.

pk
As Time has said, if the young ones cannot even imagine it, then they have certainly not felt it and therefore they could still less remember it.

I think that GMAC, wanting to avoid any debate on such a hazy thing, opted to omit it safely.

Idiom:

So X that Y

(A) so profound many young Americans are not able to imagine, even less to remember - Wrong: 1) Structure: Missing "that" 2) Concision: "cannot" is better than "are not able to" 3) Don't need "to" before "remember"

(B) so profound that many young Americans cannot imagine, much less remember - Correct

(C) so profound many young Americans cannot imagine nor even less remember - Wrong: 1) Structure: Missing "that"

(D) of such profundity many young Americans cannot imagine, even less can they remember - Wrong: 1) Structure: Missing "that" 2) Redundancy: "that" before "remember"

(E) of such profundity that many young Americans are not able to imagine, much less to remember - Wrong: 1) Concision: "cannot" is better than "are not able to" 2) Don't need "to" before "remember"

"much less" is conjunction and means And also not

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.

(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 - correct

(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
requires such x that.
(E) of such profundity that many young Americans are not able to imagine, much less to remember

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