This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
Secondary attack rate is defined as- 
Select and explain. 
A. Number of total cases developing disease within maximum incubation period, B. Number of case developing disease within incubation period following exposure to primary care, C. Number of cases developing diseare after exposure to primary case in any period of time, D. Number of cases developing after exposure to secondary case
B: Number of case developing disease within incubation period following exposure to primary care
Answer: B: Number of case developing disease within incubation period following exposure to primary care 
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