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
Dose of all is reduced in renal failure, except ? 
Select and explain. 
A. INH, B. Rifabutin, C. Ethambutol, D. Kanamycin
B: Rifabutin
Answer: B: Rifabutin 
Explanation: Ans. is 'b' i.e., Rifabutin