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': 'The cutting efficiency of a bur is improved by \nSelect and explain. \nA. Applying more pressure, B. More number of blades, C. Large size of bur, D. Rake angle', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]