This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'Folic acid metabolism is inhibited by :  a) Sulfonamides b) Methotrexate c) Nitrous oxide d) Trimethoprim e) 5–Flucytosine \nSelect and explain. \nA. acd, B. abd, C. bde, D. ace', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]