This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sensitivity, Specificity, PPV, NPV, Subject name: Social & Preventive Medicine
[{'content': 'A screening test was positive in 50% of diseased and 10% of healthy population. What is the specificity of the test? \nSelect and explain. \nA. 0.5, B. 0.9, C. 0.83, D. 0.064', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Screening Test Gold Standard Positive Negative Positive 50 10 Negative 50 90 Specificity= True Negative / True Negative + False Positives = 90/90 + 10 = 90/100 = 0.9', 'role': 'assistant'}]