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': 'All of following are true about measles except? \nSelect and explain. \nA. Maximum incidence in 6m-3 year age group, B. Best age for immunization is 9-12 months, C. Secondary attack rate is 30%, D. I.P. = 7-14 days', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Secondary attack rate is 30%", 'role': 'assistant'}]