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': '. In control of communicable diseases, the period of quarantine in respect of a disease is determined by- \nSelect and explain. \nA. Incubation period, B. Infectivity period, C. Duration of illness, D. Carrier state', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]