Secondary attack rate is defined as-
High-Yield Explanation
Ans. is 'b' i.e., Number of cases developing disease within incubation period following exposure to primary case * SAR is defined as "the number of exposed persons developing the disease within the range of incubation period, following exposure to primary case".SAR=No of exposed persons developing disease within the range of the incubation period----------------------------------------Total number of exposed/susceptible contactx 100