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
Highest bond strength is found in which generation of dentin bonding agent? 
Select and explain. 
A. 4th generation, B. 5th generation, C. 6th generation, D. 7th generation
A: 4th generation
Answer: A: 4th generation 
Explanation: Bonding strength of dentin bonding agents generations:

First -  2-3 MPa
Second – 1-5 MPa
Third – 3-13 MPa
Fourth – 13-80 MPa
Fifth – 3-75 Mpa 
Sixth – 10-75 Mpa 
Seventh – 0-60 Mpa