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 influenza - \nSelect and explain. \nA. 18 - 72 hrs, B. 1 - 6 hrs, C. 5 - 10 days, D. < 1 hrs', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]