请教大全595

595Rather than continue to produce most of the items necessary for subsistence, a growing number of farm families during the first decades of the nineteenth century began to specialize in the production of grain or cotton and to use the cash proceeds from selling their crops for buying necessities.

(A) selling their crops for buying

(B) the sales of their crops for buying

(C) their selling of crops so as to buy

(D) their selling crops for buying of（E）

(E) the sale of their crops to buy

请问为什么不能选b啊？

不是也能说use sth for (doing ) sth 得吗？

是因为要跟前面得to produce平行吗？但是to use不是已经平行了吗？

虽然题目问得很烂，不过还是请大家帮帮我解答～～

谢谢