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': 'Incidence of disease among exposed divided that of non exposed is equal to \nSelect and explain. \nA. Relative risk, B. Attributable risk, C. Odd ratio, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]