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 around: \nSelect and explain. \nA. 60%, B. 70%, C. 80%, D. 90%', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Chicken pox is highly contagious with secondary attack rates of nearly 90%. The period of communicability ranges from 1 to 2 days before onset of rash to 4 to 5 days thereafter. Ref: Park 21st edition, page 134', 'role': 'assistant'}]