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
The inner surface of ceramic veneer is etched with 
Select and explain. 
A. 50% Phosphoric acid, B. 30% Polyacrylic acid, C. 35% Citric acid, D. 5% Hydrofluoric acid
D: 5% Hydrofluoric acid
Answer: D: 5% Hydrofluoric acid 
Explanation: None