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': 'Cavosurface margin angulation in chamfer finish line is: \nSelect and explain. \nA. Always 90°, B. 90° or less than 90°, C. 90° or more than 90°, D. 120°', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]