This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Which of the following drug is an inhibitor of cytochrome p450 enzyme 
Select and explain. 
A. Ketoconazole, B. Rifampecin, C. Phenytoin, D. Phenobarbitone
A: Ketoconazole
Answer: A: Ketoconazole 
Explanation: Ketoconazole is a powerful microsomal enzyme inhibitor where as rifampicin,phenobarbitone and Phenytoin are enzyme inducers Refer KDT 7-e p26