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
Etching of dentin does not include: 
Select and explain. 
A. Removal of smear layer, B. Exposure of collagen fibres, C. Opening of dentinal tubules, D. Increases surface energy
D: Increases surface energy
Answer: D: Increases surface energy 
Explanation: None