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
All of the following about use of aerotor hand piece are false except: 
Select and explain. 
A. The sound frequency greater than 75 decibel (dB) causes damage to the ear, B. The frequency of rotation of bur is 6000-8000rpm, C. It will harm more in elderly than very young, D. Its use in younger teeth is contraindicated.
A: The sound frequency greater than 75 decibel (dB) causes damage to the ear
Answer: A: The sound frequency greater than 75 decibel (dB) causes damage to the ear 
Explanation: None