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: Anaesthesia
[{'content': 'Methemoglobinemia can be treated by: \nSelect and explain. \nA. Methylene blue, B. Vitamin K, C. Vitamin A, D. All of the above', 'role': 'user'}, {'content': "Answer: A \nExplanation: Hepatic metabolism of prilocaine generates O-toluidine, which oxidizes hemoglobin to methemoglobin. Methemoglobinemia, if severe, may be treated by the intravenous administration of methylene blue Ref: Miller's anesthesia-7th ed, Chapter 30.", 'role': 'assistant'}]