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': 'A population of 1000 people in whom the prevalence of disease XYZ is 50%. ABC screening test was used to screen disease which has specificity and sensitivity of 50 %. What is positive predictive value of screening test ABC. \nSelect and explain. \nA. 50%, B. 25%, C. 75%, D. 10%', 'role': 'user'}, {'content': "Answer: A \nExplanation: Total Population = 1000 Prevalence = 50% People have Disease = 500 Not have Disease = 500 Method 1 Test Disease [?] Th [?] A TP ? B FP ? Th C FN ? D TN ? 500 (given) 500 (given) 1000 (given) Test Disease [?] Th [?] A 250 B 250 Th C 250 D 250 Method 2 ( Baye's Theorum)", 'role': 'assistant'}]