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 progression is seen in all except: \nSelect and explain. \nA. Case control study, B. Coho study, C. RCT, D. Ecological study', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Case control study', 'role': 'assistant'}]