This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
[{'content': 'What is the numerator in the calculation the sensitivity of a test \nSelect and explain. \nA. True-Positive, B. true-negative, C. False-Positive, D. False-Negative', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Sensitivity = number of true positives / number of true positives + number of false negativesSpecificity = number of true negatives / number of true negatives + number of false positives', 'role': 'assistant'}]