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': 'In a village of 1 lakh population, among 20, 000 exposed to smoking, 200 developed cancer, and among 40,000 people unexposed, 40 developed cancer. The relative risk of smoking in the development of cancer is - \nSelect and explain. \nA. 20, B. 10, C. 5, D. 15', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., 10", 'role': 'assistant'}]