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 of the following drugs has covalent interaction with its target ? \nSelect and explain. \nA. Aspirin, B. Penicillin, C. Nitric oxide, D. Bosentan', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Covalent interaction means irreversible inhibition of the enzyme. Aspirin irreversibly acetylates the cox enzyme.', 'role': 'assistant'}]