This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2018, Subject name: Pharmacology
[{'content': 'Which of the following is not an alkylating agent:- \nSelect and explain. \nA. Melphalan, B. Cyclophosphamide, C. Busulfan, D. 5-Fluorouracil', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Melphalan Cyclophosphamide Busulfan These are alkylating agents.', 'role': 'assistant'}]