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
Methotrexate is what class of anti cancer drug - 
Select and explain. 
A. Alkylating agents, B. Antimetabolites, C. Microtubule damaging agents, D. Topoisomerase inhibitors
B: Antimetabolites
Answer: B: Antimetabolites 
Explanation: Ans. is 'b' i.e., Antimetabolites o Alkylating agents* Nitrogen mustards -Mechlorethamine, cyclophosphamide, Ifosfamide, chlorambucil, Melphalan.* Ethylenimine -Thio - TEPA* Alkyl sulfonate -Busulfan* Nitrosoureas -Carmustine, Lomustine* Triazine -Dacarbazine, Procarbazine* Others -Altretamine, cisplatin, carboplatin, oxaliplatin.o Antimetabolites* Folate antagonist- Methotrexate, Pemetrexed.* Purine antagonist-6 - Mercaptopurine, 6-Thioguanine, Azathioprine, Fludarabine.* Pyrimidine antagonist-5 - Fluorouracil, cytarabine (cytosine - arabinaside).o Vinca alkaloids - Vincristin (oncovin), vinblastin, vinorelbineo Taxanes -Paclitaxel, Docetaxelo Epipodophyllotoxin -Etoposideo Camptothecin analogue-Topotecan, Irinotecano Antibiotics-Actinomycin D (Dactinomycin), Doxorubicin, Daunorobicin (Rubidomycin), Mitoxantrone, Bleomycin, Mitomycin C.o Miscellaneous-L-Asparginase.