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': 'Interval between primary and secondary case is called as? \nSelect and explain. \nA. Generation time, B. Serial interval, C. Incubation period, D. Lead time', 'role': 'user'}, {'content': "Answer: B \nExplanation: The serial interval is generally estimated from the interval between clinical onsets, in which case it is the 'clinical onset serial interval' when these quantities are observable. It could, in principle, be estimated by the time interval between infection and subsequent transmission. Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 108", 'role': 'assistant'}]