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': 'Mechanism of action of 5–FU is : \nSelect and explain. \nA. Antimetabolite, B. Direct DNA chelating agent, C. Anti-Mitotic, D. Topoisomerase inhibitor', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]