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
Major difference between self-etch primer and total etch adhesive? 
Select and explain. 
A. Bond strength, B. Time, C. No need of wet bonding agent, D. Amount of smear layer removal
D: Amount of smear layer removal
Answer: D: Amount of smear layer removal 
Explanation: None