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
. Relative Risk can be obtained from - 
Select and explain. 
A. Case study, B. Cohort study, C. Case control study, D. Experimental study
B: Cohort study
Answer: B: Cohort study 
Explanation: None