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': 'In ceramic restoration, which can be used \nSelect and explain. \nA. 1.23% APF, B. 8% SnF2, C. 6% SnF2, D. 2% NaF', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]