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': 'Coho study reveals all except: \nSelect and explain. \nA. Incidence, B. Attributable risk, C. Relative risk, D. Odds ratio', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Odds ratio', 'role': 'assistant'}]