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
In T.B. a 'case' is: 
Select and explain. 
A. Cough, B. Sputum positive, C. Mantoux positive, D. X-ray positive
B: Sputum positive
Answer: B: Sputum positive 
Explanation: Sputum positive