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
[{'content': 'In low dose aspirin acts on : \nSelect and explain. \nA. Cyclooxygenase, B. Thromboxane A, synthase, C. PGI2 synthase, D. Lipoxygenase', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]