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 is a prodrug 
Select and explain. 
A. Enalapril, B. Clonidine, C. Salmetarol, D. Acetazolamide
A: Enalapril
Answer: A: Enalapril 
Explanation: All ACE inhibitor are prodrug except captopril and lisnopril