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
A patient with sputum positive pulmonary tuberculosis is on ATT for the last 5 months but the patient is still positive for AFB in the sputum. This case refers to - 
Select and explain. 
A. New case, B. Failure case, C. Relapse case, D. Drug defaulter
B: Failure case
Answer: B: Failure case 
Explanation: Ans. is 'b' i.e., Failure case