Original sentence -
While Marcus Garvey had proposed ideas similar to those voiced by black power advocates Stokeley Carmichael and Malcolm X,
they never created the same dynamic force that
they would later create.
Confusing antecedents for "they". They could be ideas or advocates.
"While" brings contrast. The first half of the sentence is about
similarity of Garvey's ideas to those of advocates, the 2nd half
- must bring some
differences. - should talk limited effects of Marcus's ideas.
Let's look at choices.
(A) they never created the same dynamic force that they would
Incorrect for antecedents of "they"(B) Garvey never created the dynamic force that Carmichael and Malcolm X would
Looks fine with no confusion. (C) they never created the same dynamic force that he would
The 2nd part should talk limited effects of Marcus's ideas. (Not the limited effects of advocates')(D)
he never created the same dynamic force that
he would
The 2nd part must bring some differences in the effect.(E) Garvey’s message never having created the same dynamic force that they will
This lacks the main verb and hence does not complete the sentence.IMO
B