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 an example for which of the following class of drugs? 
Select and explain. 
A. Antibiotic, B. Alkylating agent, C. Biologic response modifier, D. Folic acid analogue
D: Folic acid analogue
Answer: D: Folic acid analogue 
Explanation: Ans: D (Folic acid analogue) Ref: The Pharmacological basis of therapeutics bv Goodman & Gilman - 12th edition, page no. 1669 -767/Explanation:"Methotrexate is an anti-metabolite which is a folic acid analogue." Ref: G&GClassification of Anti-Cancer DrugsAnti-metabolitesPemetrexed5 FUCapecitabineCytarabineGemcitabine5-aza-cytidineAlkylating agentsCyclophosphamideMelphalanChlorambucilProcarbazineBusull'anDacarbazineCisplatinOxaliplatinAntibioticsDoxorubicinDuunorubicinDactinomycinNatural products includeVinblastineVincristinePacliiaxelIrinotecanBiologic response modifiers includeInterferon alfaInterleukin-2Other categoriesTyrosine kinase inhibitors - imatinib, Sunitinib, DasatinibmTOR inhibitors - TemsirolimusProtea some inhibitors - Bortezomib