This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
True about cross section study - 
Select and explain. 
A. Prevalence study, B. Useful for chronic disease, C. Simple study, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Ans. is 'd' i.e., All of the above Cross - sectional studiesCross sectional study is the simplest form of an observational study.It is also known as prevalence study.It is based on a single examination of a cross - section of population at one point of time.Results of this examination can be projected on the whole population.Cross-sectional study tells about the distribution of a disease rather than its etiology.Cross-sectional studies can be thought of as providing a snapshot of the frequency and characteristic of a disease in a population at a paicular point in time.Cross-sectional study is more useful for chronic disease.As population is studied at once, no follow-up is required.