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
Case finding in RNTCP is based on? 
Select and explain. 
A. Sputum culture, B. Sputum microscopy, C. X-ray chest, D. PCR antibody detection
B: Sputum microscopy
Answer: B: Sputum microscopy 
Explanation: Ans. is 'b' i.e. Sputum microscopy Sputum smear examination by direct microscopy is the method of choice for case detection. Two sputum samples are collected.