GMAT Sentence Correction (SC) | Re: Problem in understanding the "as much as" construction.

Retailers reported moderate gains in their November sales, as much becauseof their sales of a year
earlier being so bad as that shoppers were getting a head start on buying their holiday gifts.
A. of their sales of a year earlier being so bad as that
B. of their sales a year earlier having been as bad as because
C. of their sales a year earlier being as bad as because
D. their sales a year earlier had been so bad as because
E. their sales of a year earlier were as bad as that