大全338

        If a single strain of plant is used for a given crop over a wide area, a practice fostered by modern seed-marketing methods, it increases the likelihood that the impact of a single crop disease or pest will be disastrous.

(A) If a single strain of plant is used for a given crop over a wide area, a practice fostered by modern seed-marketing methods, it

(B) If a single strain of plant is used for a given crop over a wide area, as is fostered by modern seed-marketing methods, it

(C) A practice fostered by modern seed-marketing methods, a single strain of plant used for a given crop over a wide area

(D) A single strain of plant used for a given crop over a wide area, a practice fostered by modern seed-marketing methods,（E）

(E) The use of single strain of plant for a given crop over a wide area, a practice fostered by modern seed-marketing methods, [E]*

A是什么问题呢