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
In control of communicable diseases, the period of quarantime in respect of a disease is determined by- 
Select and explain. 
A. Incubation period, B. Infectivity period, C. Duration of illness, D. Carrier state
A: Incubation period
Answer: A: Incubation period 
Explanation: .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