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 is P-Glycoprotein inhibitor 
Select and explain. 
A. Rifampicin, B. Phenytoin, C. Griseofulvin, D. Ketoconazole
D: Ketoconazole
Answer: D: Ketoconazole 
Explanation: Drugs like cyclosporine, tacrolimus, quinidine, diltiazem, verapamil, itraconazole, ketoconazole, amiodarone inhibit P-Glycoprotein and cause drug toxicity.