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': "'Relative risk' is: \nSelect and explain. \nA. Risk among exposed/Risk among non-exposed, B. Risk among exposed/Risk in total population, C. Risk among exposed/Risk among exposed-Risk in new exposed, D. None of the above", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Risk among exposed/Risk among non-exposed', 'role': 'assistant'}]