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 drugs is useful in the treatment of infection by Mycobacterium avium complex? 
Select and explain. 
A. Isoniazid, B. Clarithromycin, C. Cycloserine, D. Rifampicin
B: Clarithromycin
Answer: B: Clarithromycin 
Explanation: Treatment of MAC infection is REC (Rifabutin + Ethambutol + Clarithromycin)
Clarithromycin alone can be used for the prophylaxis of MAC infections in HIV positive patients.
Azithromycin can also be used in place of clarithromycin.