Which of the following best complete the passage above?
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
Referrence key is (A)
但是我完全看不懂A在說什麼
我選(C)
我覺得c有解釋到爲什麼不需要用S. simulans來做為treatment
不過我承認(c)長得確實很像ETS的標準引誘選項
但是在看不懂A的情況下 我還是選了

請大大指點