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
Which one of the following acids is generally recommended for etching tooth structure? 
Select and explain. 
A. Maleic acid, B. Polyacrylic acid, C. Phosphoric acid, D. Tartaric acid
C: Phosphoric acid
Answer: C: Phosphoric acid 
Explanation: Although some of the self-etch bonding systems use milder acid, the primary acid system used for etching tooth structure is phosphoric acid.