This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
[{'content': 'Acute puerperal mastitis. Most common organism is \nSelect and explain. \nA. Staphylococcus aureus, B. Streptococcus pyogenes, C. Streptococcus pneumonia, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Staphylococcus aureus', 'role': 'assistant'}]