This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
[{'content': 'In control of communicable diseases, the period of quarantime 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: .quarantine has been defined as the limitation of freedom of movement of such well persons or domestic animals exposed to communicable disease for a period of time not longer than the longest usual incubation period of the disease, in such a manner as to prevent effective contact with those not so exposed,so its communicability can be attributed to the incubation period. ref:park&;s textbook,22nd edition,pg no 112', 'role': 'assistant'}]