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
[{'content': 'Partial dissolution of smear layers takes place in: \nSelect and explain. \nA. 1st generation, B. 2nd generation, C. 3rd generation, D. None', 'role': 'user'}, {'content': 'Answer: C \nExplanation: In 1st and 2nd generation, smear layer\xa0is preserved.', 'role': 'assistant'}]