This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disease Causation, Measurements, Milestones, Subject name: Social & Preventive Medicine
[{'content': 'A couple has 4 children, all unvaccinated for Measles. A child got Measles on 5 August 2015. Two other children developed Measles by 15 August 2015. Secondary attack rate is: \nSelect and explain. \nA. 0%, B. 33%, C. 66%, D. 75%', 'role': 'user'}, {'content': 'Answer: C \nExplanation: In the given question, One primary case given rise to two secondary cases Total susceptible = 3 (4 children minus primary case) SAR = No. of secondary cases/ Total susceptibles X 100 So, SAR = 2/3 X 100= 66.6%', 'role': 'assistant'}]