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': 'The inner surface of ceramic veneer is etched with \nSelect and explain. \nA. 50% Phosphoric acid, B. 30% Polyacrylic acid, C. 35% Citric acid, D. 5% Hydrofluoric acid', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]