This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
[{'content': 'Incubation period of swine flu- \nSelect and explain. \nA. 1-3 days, B. 2-3 weeks, C. 10-15 days, D. 5 weeks', 'role': 'user'}, {'content': "Answer: A \nExplanation: (ref:Park's text book 23rd edition) Incubation period of swine flu is 2 - 3 days. It is caused by pandemic influenza A (H1N1) It can infect Lower respiratory tract and causes rapidly progressive pneumonia.", 'role': 'assistant'}]