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
About acid etching of dentin all are true, except: 
Select and explain. 
A. It removes smear layer, B. It expose collagen, C. It opens dentinal tubules, D. It increase surface tension
D: It increase surface tension
Answer: D: It increase surface tension 
Explanation: None