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
In a given population, prevalence of a disease can be rapidly determined by- 
Select and explain. 
A. Case control study, B. Cross over study, C. Cross sectional study, D. Double blind study
C: Cross sectional study
Answer: C: Cross sectional study 
Explanation: . cross sectional study is a simplest form of an observational study,which are more useful in the cases of chronic diseases.cross sectional studies are also employed in the calculation of prevalence,.it provides only very little information about the natural history of disease or about the rate of occurrence of new cases. ref:park&;s textbook of preventive and social medicine,22nd edition,pg no 67