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: Microbiology
Infectivity period of chicken pox 
Select and explain. 
A. 2 days before & 5 days after appearance of rash, B. 1 week before & 1 week after onset of rash, C. Till the fever subsides, D. 10 days after onset of rash
B: 1 week before & 1 week after onset of rash
Answer: B: 1 week before & 1 week after onset of rash 
Explanation: Infectivity period of chicken pox is 2 days before & 5 days after onset of rash.