This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
Thromboxane A, is produced mainly by 
Select and explain. 
A. Vascular endothelium, B. Platelets, C. Liver, D. Damaged tissue
B: Platelets
Answer: B: Platelets 
Explanation: Platelet Activating Factor(PAF) secreted by platelets act G protein-coupled receptor to produce arachidonic acid derivative like Thromboxane A2 Ref: Ganong's Review of Medical Physiology Twenty-Third Edition pg no:75 Thromboxane A2 is produced by activated platelets during hemostasis and has prothrombotic activity. It activates new platelets and increase platelet aggregation.