(A) do so on this one occasion because she firmly believed that many minority people, likely most, would agree
(B) speak on this one occasion since she firmly believed that many minority people, likely most, would have agreed
(C) so speak on this one occasion due to her firmly believing that many minority people, even most, would likely agree
(D) do so on this one occasion because she firmly believed that many minority people, if not most, would agree
(E) do so on this one occasion since she firmly believed many minority people, and even most, would likely agree
Solution:
Idiom + Tense
B is wrong due to use of have agreed.
C is wrong as do is missing.
E uses an extra word likely. Also, because is better than since. Thirdly, and even most is awkward.
A, by using likely most fails to convey the much needed contrast for the effective meaning of the sentence. D does so by using the correct term if not most.
D is the best choice.
Sentence Correction - 1000 Questions with Solution: