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': 'Predictive value of a positive test is defined as ? \nSelect and explain. \nA. True + ve/true + ye + false - ye x 1 00, B. True + ye/true + ye + false + ye x 100, C. False + ve/true + ve + false + vex 100, D. False + ve/true + ve + false - vex 100', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is `b' i.e., True + ye (true + ye + false + ye) x 100", 'role': 'assistant'}]