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 antiplatelet drugs is a prodrug: 
Select and explain. 
A. Clopidogrel, B. Tirofiban, C. Aspirin, D. Dipyridamole
A: Clopidogrel
Answer: A: Clopidogrel 
Explanation: ADP receptor antagonists, ticlopidine and clopidogrel are prodrugs.