明天考试，求一道CR的GWD原题

GWD21-Q21:

Which of the following most logically completes the passage?

Mastitis is an infection of the udder in cows that, although not dangerous, causes them to give poor-quality milk.  Most cases of mastitis are caused by the bacterium Staphylococcus aureus, against which antibiotics are ineffective.  However, a related bacterium, Staphylococcus simulans, quickly clears up even severe infections of S. aureus simply by displacing the bacteria.  S. simulans is nevertheless unlikely to become the preferred treatment for cases of mastitis, since ______.

A.      certain dangerous bacteria that normally cannot take hold can do so in the presence of S. simulans

B.      the current resistance of S. aureus to antibiotics derives in part from a past pattern of overuse of those antibiotics

C.      the milk from cows infected with S. aureus is generally not of such poor quality as to be entirely unusable

D.      careful farming practice can reduce the incidence of mastitis to a minimum

E.       the only symptom of mild cases of mastitis is the deterioration in the quality of the milk produced

answer: A

但是和作者提供的有区别，估计变体了。

如果问假设的话，不难推测可能是：The presence of S.simulans will not stimulate certain dangerous bacteria that normally cannot take hold. 应该大体是这个方向，因为出题人也会忠于原文，懒得去想一个更好的答案了吧。

感谢感谢~~