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': 'Serial interval is? \nSelect and explain. \nA. Time interval between invasion of infection and appearance of first sign or symptom, B. Time between onset of primary case and secondary case, C. Interval of time between receipt of infection by a host and maximum inefectivity, D. Time in which infectious agent is transferred from one host to another', 'role': 'user'}, {'content': "Answer: B \nExplanation: SERIAL INTERVAL is the gap in time between the onset of the primary case and the secondary case.it helps to get a distribution of secondary cases from which we can guess the incubation period of diseasered:park's textbook of preventive and social medicine,22 nd edition,pg no 96", 'role': 'assistant'}]