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

What is diff between A and E

I too narrowed it down to A & E. Went with A as a final answer.