This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Screening, Subject name: Social & Preventive Medicine
[{'content': 'Denominator of positive predictive value is \nSelect and explain. \nA. True positive + False positive, B. True positive + False negative, C. False positive + True negative, D. False positive + false negative', 'role': 'user'}, {'content': 'Answer: B \nExplanation: .predictive value of a positive test is calculated as true positive divided by the sum of true positive and false positive expressed in percentage ref:park&;s textbook ,22 nd edition,pg no 130', 'role': 'assistant'}]