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 one of the following drugs is not used in the treatment of mycobacterium avium intercellulare infection ? 
Select and explain. 
A. Clarithromycin, B. Eflornithine, C. Ethambutol, D. Rifabutin
B: Eflornithine
Answer: B: Eflornithine 
Explanation: None