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
Which of the following study type is the best to study natural history of a disease? 
Select and explain. 
A. Coho Study, B. Case Control Study, C. Randomized Control Trials, D. Interventional Studies
A: Coho Study
Answer: A: Coho Study 
Explanation: Natural history of a disease is best studied by coho studies. But these studies tend to be costly and laborious. Hence crossectional and retrospective studies are often undeaken to study natural history of any disease. Ref: Park, 21st Edition, Page 32.