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
Which of the following drugs has covalent interaction with its target ? 
Select and explain. 
A. Aspirin, B. Penicillin, C. Nitric oxide, D. Bosentan
A: Aspirin
Answer: A: Aspirin 
Explanation: Covalent interaction means irreversible inhibition of the enzyme. Aspirin irreversibly acetylates the cox enzyme.