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': 'Dilantain (Phenytoin) is known to cause: \nSelect and explain. \nA. Folic acid deficiency, B. Biotin deficiency, C. Thiamine deficiency, D. Riboflavin deficiency', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Folic acid deficiency', 'role': 'assistant'}]