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: Pharmacology
Which of the following anti-TB drug requires acidic medium for action? 
Select and explain. 
A. Isoniazid, B. Rifampicin, C. Pyrazinamide, D. Ethambutol
C: Pyrazinamide
Answer: C: Pyrazinamide 
Explanation: Pyrazinamide requires acidic medium for action and active only against intracellular mycobacteria.