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
Denominator in Incidence rate is? 
Select and explain. 
A. Total observed population, B. Total population at risk in a year, C. Total live births, D. Total new cases in a year
B: Total population at risk in a year
Answer: B: Total population at risk in a year 
Explanation: ANSWER: (B) Total population at risk in a yearREF: Park's 22 Ed page 58Indirect repeat Community medicine Post diploma June 2012