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: Dental
[{'content': 'Which one of the following is used to bleach a discolored endodontically treated tooth? \nSelect and explain. \nA. Ether, B. Chloroform, C. Superoxol, D. Sodium hypochlorite', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]