This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Classification, Coho Study, Subject name: Social & Preventive Medicine
Best epidemiological study to know Causality is: 
Select and explain. 
A. Coho study, B. Case control study, C. Cross sectional study, D. Ecological study
A: Coho study
Answer: A: Coho study 
Explanation: Temporal association Implies 'cause precedes effect' or 'effect follows cause'. Is 'most impoant criterion' of casual association. Is ' best established by a coho study' (Especially concurrent coho study) as coho study is forward study.