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: Dental
[{'content': 'A total of 21 people have been in contact with patient  positive for SARS COV 2 and these people do not show any symptoms or signs of COVID 19. What is time duration for which they must be quarantined? \nSelect and explain. \nA. Period of communicability, B. Median incubation period, C. Minimum incubation period, D. Maximum incubation period', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Quarantine\xa0has\xa0been\xa0defined\xa0as\xa0"the\xa0limitation\xa0of freedom\xa0of\xa0movement\xa0of such\xa0well\xa0persons\xa0or domestic animals\xa0exposed\xa0to\xa0communicable\xa0disease\xa0for\xa0a\xa0period\xa0of time not longer than the longest usual incubation period of the disease, in\xa0 such manner as to\xa0 prevent effective contact with\xa0those not so exposed".\xa0Quarantine measures are also\xa0"applied\xa0by\xa0a\xa0health authority to a\xa0ship,\xa0an aircraft,\xa0 a train, road vehicle, other means of transport or container, to prevent\xa0 the\xa0spread\xa0of\xa0disease,\xa0reservoirs\xa0of\xa0disease or vectors of disease".\nQuarantine\xa0may\xa0comprise\xa0\xa0\n(a)\xa0 absolute\xa0quarantine,\xa0as defined\xa0above;\xa0\xa0\n(b)\xa0 modified\xa0quarantine,\xa0e.g.,\xa0 a selective partial limitation of freedom of movement, such as exclusion equilibrium between\xa0host\xa0and\xa0environment\xa0by encouraging\xa0some\xa0ecological influences\xa0 and inhibiting others.', 'role': 'assistant'}]