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': 'Which enzyme is irreversibly inhibited by aspirin? \nSelect and explain. \nA. Lipooxygenase, B. Cyclooxygenase, C. Thromboxane synthase, D. Phospholipase', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Cyclooxygenase", 'role': 'assistant'}]