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: 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: Swine flu\n\nSwine flu, also called swine influenza, or pig influenza, is caused by influenza virus.\nIt is mainly occurs in swines (pigs) and occasionally transmitted to human.\nIt is usually caused by influenza virus type A (H1-N1).\nIncubation period is about 1-3 days and the symptoms of swine flu in humans are similar to most influenza infections, e.g. fever, cough, rhinorrhea, fatigue and headache.', 'role': 'assistant'}]