This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Neoplastic Agents, Subject name: Pharmacology
Which is not an Antimetabolite? 
Select and explain. 
A. Methotrexate, B. 5 Fluorouracil, C. Gemcitabine, D. Vinca alkaloids
D: Vinca alkaloids
Answer: D: Vinca alkaloids 
Explanation: ANSWER: (D) Vinca alkaloidsREF: Harrisons 17th edition chapter 8, KDT, Goodman GillmanSee APPENDIX-37 for "CLASSIFICATION OF CANCER CHEMOTHERAPY AGENTS"