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': '10% KNO3 is used to \nSelect and explain. \nA. treat hypersensitive dentin, B. reduce caries, C. as an acid etchant, D. as a base below restoration', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]