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': 'Which vitamin is most likely to be deficient in patients on treatment with isoniazid : \nSelect and explain. \nA. Vitamin B1, B. Vitamin B2, C. Vitamin B6, D. Vitamin B12', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]