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
All of the following statements regarding case control and coho studies are true, except- 
Select and explain. 
A. Coho studies are chosen based on history of 'Exposure', B. Coho studies require longer time frame than case control studies, C. Coho studies are suitable to investigate 'rare' disease, D. Coho studies yield information about more than one disease
C: Coho studies are suitable to investigate 'rare' disease
Answer: C: Coho studies are suitable to investigate 'rare' disease 
Explanation: Case-control study is useful to investigate rare diseases or diseases about which little is known. But a disease which is rare in the general population (e.g, leukemia in adolescence) may not be rare in special exposure groups (e.g prenatal X- rays) (refer pgno:74 park 23 rd edition)