This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bleeding Disorders, Subject name: Pathology
[{'content': 'Platelet aggregation is caused by? \nSelect and explain. \nA. Nitrous oxide, B. Thromboxone A2, C. Aspirin, D. PGE2', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b). Thromboxone A2(Ref: Robbins 9th/pg 116-117)Thromboxone A2 (TXA2)It is produced by activated platelets and has prothrombotic propertiesIt is an Arachidonic acid metabolite of COX pathwayFunctions: It is a potent platelet aggregator & vasoconstrictorIts effect is neutralized by prostacyclin (PGI2)', 'role': 'assistant'}]