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': 'Causal association factors can be revealed by ? \nSelect and explain. \nA. Case control study, B. Coho study, C. Cross sectional study, D. Experimental study', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Case Control study o In a case control study we proceed from the effect to cause therefore we can study many causal associated factors at a time.o Whereas in coho study we proceed from the cause to effect, therefore we can get to several diseases associated with the cause but we can not study many causal factors at a time.", 'role': 'assistant'}]