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: Pathology
[{'content': 'True about thromboxane A2: \nA) Formed by platelets\nB) Formed from PGG2/PGH2\nC) Prothrombogenic\nD) Vasoconstricter\nE) Vasodilator \nSelect and explain. \nA. ABC, B. ABCDE, C. ABCD, D. ACB', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]