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
[{'content': 'Which is not an Antimetabolite? \nSelect and explain. \nA. Methotrexate, B. 5 Fluorouracil, C. Gemcitabine, D. Vinca alkaloids', 'role': 'user'}, {'content': 'Answer: D \nExplanation: ANSWER: (D) Vinca alkaloidsREF: Harrisons 17th edition chapter 8, KDT, Goodman GillmanSee APPENDIX-37 for "CLASSIFICATION OF CANCER CHEMOTHERAPY AGENTS"', 'role': 'assistant'}]