请教各位啊。。。

HotCold

GWD-24-29.

Plant scientists have been able to genetically engineer vegetable seeds
        to produce crops that are highly resistant to insect damage. Although
        these seeds currently cost more than conventional seeds, their cost is likely to decline. Moreover, farmers planting them can use far less pesticide, and most consumers prefer vegetables grown with less pesticide,
        therefore, for crops for which these seeds can be developed, their use is likely to become the norm.

 

Which of the following would be most useful to know in evaluating the
        argument above?

 

A.      Whether plant scientists have developed insect-resistant seeds
        for every crop that is currently grown commercially

B.      Whether farmers typically use agricultural pesticides in larger
        amounts than is necessary to prevent crop damage.

C.      Whether plants grown from the new genetically engineered seeds
        can be kept completely free of insect damage.

D.      Whether seeds genetically engineered to produce insect-resistant
        crops generate significantly lower per acre crop yields than do
        currently used seeds.

E.       Whether most varieties of crops currently grown commercially have
        greater natural resistance to insect damage than did similar varieties in the past.

 请问下各位牛牛哦，为什么B不对啊？为什么是D呢？

 非常感谢啊！！！