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: ENT
Impedance audiometry is done using frequency probe of- 
Select and explain. 
A. 220 Hz, B. 555 Hz, C. 440Hz, D. 1000 Hz
A: 220 Hz
Answer: A: 220 Hz 
Explanation: None