GWD 3-11

Q11:

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.

1. of their sales of a year earlier being so bad as that


2. of their sales a year earlier having been as bad as because


3. of their sales a year earlier being as bad as because


4. their sales a year earlier had been so bad as because


5. their sales of a year earlier were as bad as that

answer: D

请问D中, had been怎么解释，为什么用被动？thanks!!

Had been 是 are 的过去完成时态,不是被动.

谢谢！