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': 'Definition of Population attributable risk \nSelect and explain. \nA. Estimate of amount of disease that can be reduced if risk factor is modified/ eliminated, B. Difference in risk of exposed and non-exposed groups, C. Risk of disease among exposed as compared to nonexposed, D. Extent to which disease can be attributed to risk factor under study', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]