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
Partial dissolution of smear layers takes place in: 
Select and explain. 
A. 1st generation, B. 2nd generation, C. 3rd generation, D. None
C: 3rd generation
Answer: C: 3rd generation 
Explanation: In 1st and 2nd generation, smear layer is preserved.