This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Biostatistics, Subject name: Social & Preventive Medicine
[{'content': 'Positive predictive value of a screening test is measured by- \nSelect and explain. \nA. True positive x 100 (True positive + False positive), B. True negative x 100 (false positive + false negative), C. True positive x 100\\/ (True positive + False negative), D. True negative x 100 (True positive + False negative', 'role': 'user'}, {'content': 'Answer: A \nExplanation: .', 'role': 'assistant'}]