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
[{'content': 'Cause to effect progression is seen in all except? \nSelect and explain. \nA. Case control study, B. Ecological study, C. Coho study, D. Randomized control trial', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Case control study o Case-control study proceeds backward from effect to cause, i.e. disease has already occured in subjects. o All other studies proceeds forward from cause to effect, i.e. disease has not occured in subjects.", 'role': 'assistant'}]