is answer A

as
premise: a related bacterium, Staphylococcus simulans, quickly clears up even severe infections of S. aureus simply by displacing the bacteria
coclusion : simulans is nevertheless unlikely to become the preferred treatment for cases of mastitis,

we have to find out why simulans is not a preferred treatment even clears up the infection

there could be many reason for that. May be simulans is causing another disease

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

please correct me if I am wrong

alltimeacheiver wrote: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

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.
[Correct]
B. the current resistance of S. aureus to antibiotics derives in part from a past pattern of overuse of those antibiotics
[Incorrect] Drop in body resistance due to over usage of Antibiotics ..looks okay but not giving good answer...
C. the milk from cows infected with S. aureus is generally not of such poor quality as to be entirely unusable
[Incorrect] we need to concentrate about why simulan treatment is not preferred.
D. careful farming practice can reduce the incidence of mastitis to a minimum
[Incorrect] Out of scope
E. the only symptom of mild cases of mastitis is the deterioration in the quality of the milk produced
[Incorrect] Again question is on treatement.

Let some expert comment on this.... IMO A