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
Which of the following is not an alkylating agent:- 
Select and explain. 
A. Melphalan, B. Cyclophosphamide, C. Busulfan, D. 5-Fluorouracil
D: 5-Fluorouracil
Answer: D: 5-Fluorouracil 
Explanation: Melphalan Cyclophosphamide Busulfan These are alkylating agents.