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': 'If a bur cuts a hole measurably larger than the head diameter, the defect is usually because of: \nSelect and explain. \nA. Concentricity, B. Runout, C. Wornout blades, D. Altered taper angle', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Runout is the more significant term clinically, because it is the primary cause of vibration during cutting and is the factor that determines the minimum diameter of the hole that may be prepared by a given bur. Burs normally cut holes measurably larger than the head diameter because of runout defects.', 'role': 'assistant'}]