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': 'Atwoods classification Order IV corresponds to \nSelect and explain. \nA. Knife edged ridge, B. High well rounded, C. Low well rounded, D. Depressed', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]