Sentence Correction

It seemed that hardly any vote was cast on the Senate or House floor without some calculation as to how it might affect the midterm election.
(A) without some calculation as to how
(B) without there is some calculation as to how
(C) without that there is some calculation as to how
(D) without some calculation as how
(E) without some calculation to how

I crossed out B and C because they are wordy(it can be concise). I also X-ed out D because "as how" does not make sense.(illogical). [spoiler]Between A and E, I chose E but the OA says A. Can anyone explain this?[/spoiler] Thank you.

gmat test grammar error and logic of meaning. check grammar and meaning logic. alway follow order or you die

lets check grammar

"without" can not come before a clause

a preposition can not be used before that clause,

"as to" is correct preposition