XDF 124-10

.        In the face of widespread concern about environmental waste, compact disc manufacturers are attempting to find a replacement for the disposable plastic box in which they package their product.

(A) the disposable plastic box in which they

(B) the disposable plastic box where they

(C) a disposable plastic box in which to

(D) disposable plastic boxes inside which they（A）

(E) the disposable plastic boxes in which to

ANSWER： A

B 为什么不对？  in which 和where 区别？？？