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': 'Secondary attack rate of chicken pox is - \nSelect and explain. \nA. 60, B. 50, C. 90, D. 40', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Secondary attack rate of chicken pox is high, upto 90%.', 'role': 'assistant'}]