Meaning: there was a lot of scandals in 1984 election season, moreover one scandal was the most controversial among others.

So we are comparing one the most controversial scandal with others, all scandals in the past - we need past simple to describe this events. (A), (D) and (E). To compare two nouns better to use comparative construction "more...than". (A) and (D) out one more time.
Split between "maybe" and "perhaps" is not essential, both of them conveys the same logic.


(A) maybe none is controversial as

We have (B) and (C), to me both of them gramatically okey, in (B) "it is" acts as a placeholder and seems making this answer wordy, but in comparison with (C), (B) is not good enough to me (C) elegantly conveys the same meaning

(B) maybe it is none that was more controversial than

(C) perhaps none was more controversial than



(D) it maybe that none is more controversial as

(E) perhaps it is none that is more controversial than

C is the answer
_________________