问：补充题250题中的217题（讨论连接里没有~~）

217.
                Although some officials noted that using machines for farming in China costs more than traditional hand cultivation, the mechanization of farming in the village of Long Bow doubled the corn yield while the previous year’s costs were cut in half.

(A) mechanization of farming in the village of Long Bow doubled the corn yield while the previous year’s costs were cut in half

(B) mechanization of farming in the village of Long Bow doubled the corn yield while cutting costs to half those of the previous year

(C) mechanization of farming in the village of Long Bow doubled the corn yield as cost were cut to half of the previous year’s

(D) farming mechanization in the village of Long Bow doubled the corn yield as it cut in half the previous year’s costs（B）

(E) farming mechanization in the village of Long Bow doubled the corn yield while costs were cut to half that of the previous year

答案是B，A为什么错？还有B里面的half 后面难道不应该紧跟of么？另外，mechanization of farming和farming mechanization 是不是都可以的？谢谢