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
If less than 27% H3PO4 is used for acid etching then, 
Select and explain. 
A. It precipitates less., B. It forms dicalcium phosphate monohydrate., C. The formed precipitate cannot be rinsed off., D. All of the above.
D: All of the above.
Answer: D: All of the above. 
Explanation: None