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': 'In T.B/ a ‘case’ is” \nSelect and explain. \nA. Cough, B. Mantoux positive, C. Sputum positive, D. X-ray positive', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]