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
Depth of demineralization for dentin is: 
Select and explain. 
A. 10 micron, B. 7.5 micron, C. 6 micron, D. 20 micron
B: 7.5 micron
Answer: B: 7.5 micron 
Explanation: In enamel, the resin tags are approximately 6 µm in diameter and 10 to 20 µm in length and lead to micromechanical interlocking.
Phillips 12th edition page 260
Dentin is demineralized by up to approximately 7.5 µm depending on the type of acid, application time, and concentration.

Sturdevant 7th edition page 144