This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiological Study, Subject name: Social & Preventive Medicine
Incidence is calculated by- 
Select and explain. 
A. Retrospective study, B. Prospective study, C. Cross sectional study, D. Random study
B: Prospective study
Answer: B: Prospective study 
Explanation: Ans. is 'b' i.e., Prospective study o Incidence rate is measured by cohort study, also known as prospective study.Epidemiological studyParameter obtainedo Case control studyOdds ratioo Cohort studyIncidence rateRelative riskAttributable riskPopulation attributable risko Cross - sectional studyPrevalenceo Ecological studyGroup characteristics