This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
[{'content': 'All of the following are true about varicella Except \nSelect and explain. \nA. Period of communicability is 2 days after rash, B. All stages of rash are seen at the same time, C. Secondary attack rate is 90%, D. Rash commonly seen in flexor area', 'role': 'user'}, {'content': 'Answer: A \nExplanation: - Period of communicability is 1 to 2 days before the appearance of rash and 4 to 5 days thereafter.- Incubation period 14-16 days (10-21)- The second attack rate in household contacts approaches 90%- In 10-30% may reactivate resulting in herpes zosterPark 23e pg: 144', 'role': 'assistant'}]