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
Prevalence of cataract at one point of time can be determined by - 
Select and explain. 
A. Longitudinal study, B. Cross sectional study, C. Surveillance, D. Coho study
B: Cross sectional study
Answer: B: Cross sectional study 
Explanation: Cross-sectional study provides information about disease prevalence but it provides very little information about the natural history of disease or rate of occurrence of new cases (refer park pgno:69 23 rd edition)