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': 'When undertaking bleaching of vital teeth of the\nfollowing are done except: \nSelect and explain. \nA. Prophylaxis, B. Use of protective eye glasses, C. Use of local anaesthesia, D. Polishing after treatment', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]