This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology and breast, Subject name: Surgery
[{'content': "TRUE about bacterial mastitis is \nSelect and explain. \nA. Exclusively occurs is lactating breasts, B. Cleaningn baby's mouth offers protection, C. Most commonly caused by staphylococcus aureus, D. Fluctuation is an early sign of breast abscess", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Most cases are caused by S. aureus and, if hospital acquired, are likely to be penicillin resistant. Most common variety of mastitis. Ref : Bailey and love 26thE pg820', 'role': 'assistant'}]