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': 'Diagnosis of TB acc to DOTS ? \nSelect and explain. \nA. 1 out of 2 samples positive, B. 2 out of 3 samples positive, C. 3 out of 3 samples positive, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]