This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
Which of the following is a pro drug? 
Select and explain. 
A. Hydralazine, B. Clonidine, C. Captopril, D. Enalapril
D: Enalapril
Answer: D: Enalapril 
Explanation: ACEI inhibitors are all prodrugs except captopril and ramipril. hydralazine is an aeriolar dilator enalapril is an ACEI inhibitor used in hypeensive emergencies. Ref: KDT 6/e pg 20.