Retailers reported moderate gains in their November sales, as much because of 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
Is it ok to use past perfect when it is already mentioned "a year earlier", which shows something is done before in time? Can anyone explain it? Thanks in advance.