This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Histamine, 5-HT and PGs, Subject name: Pharmacology
Aspirin is used for secondary prevention of ischemic hea disease because it:- 
Select and explain. 
A. Inhibits TXA2 synthesis by platelets, B. Inhibit prostacyclin synthesis, C. Inhibits release of EDRF, D. Inhibit synthesis of endothelins
A: Inhibits TXA2 synthesis by platelets
Answer: A: Inhibits TXA2 synthesis by platelets 
Explanation: Aggregatory substances: TXA2 ADP Inhibits aggregation: PGI2. Aspirin is Irreversible inhibitor of COX - thus preventing TXA2 formation & aggregation of PLATELETS.