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': 'Application of incubation period is all except \nSelect and explain. \nA. To differentiate primary case from secondary cases, B. To prevent infection to the contacts of the infected person, C. To find out time for quarantine, D. To find out time for isolation', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]