A. After formation of scab.
B. Just before and after onset of rash.
C. One week before onset of rash.
D. During convelescence.
The condition shown in the picture above represents chicken pox.
Spread of chicken pox is maximum just before and after onset of rash.
Communicable period (period of maximum infectivity) in chicken pox is 2 days before to 5 days after onset of rash.