Answer:
C
Step-by-step explanation:
Frequent exposure of Staphylococcus aureus methicillin by humans – such as through excessive use of non-prescribed antibiotics-, the rate of mutations in the bacteria population increases. This results to increases chances that a mutant will develop that is resistant to methicilin. Once a mutant develops, its population increases even when exposed to the antibiotic because it is resistant to methicilin. Bacteria also exchange genetic material horizontally so the gene for resistance will quickly spread in a population. This results in MRSA that is hard to eradicate.