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': 'Formula to calculate sensitivity of a screening test ? \nSelect and explain. \nA. True positive/true positive + false negative, B. True negative/true positive + false negative, C. True positive/true negative + false positive, D. True negative/true negative + false positive', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., True positive/true positive + false negative", 'role': 'assistant'}]