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
The advantage of ultra speed hand piece is: 
Select and explain. 
A. Low frequency and high amplitude make the patient comfortable, B. High frequency and low amplitude do not let the patient perceive pain, C. Less trauma, D. None of the above
B: High frequency and low amplitude do not let the patient perceive pain
Answer: B: High frequency and low amplitude do not let the patient perceive pain 
Explanation: None