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
The Framingham hea study is an example of- 
Select and explain. 
A. Case-control study, B. Coho study, C. Randomized controlled trial, D. Cross-sectional study
B: Coho study
Answer: B: Coho study 
Explanation: Coho study is also known as incidence study. The cohos are identified prior to the appearance of disease under investigation. The study group so defined are observed over a period of time to determine the frequency of disease among them. Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 83