The correct option is B 30,000 Hz
Answer is B.
Ultrasound is acoustic (sound) energy in the form of waves having a frequency above the human hearing range and hence, it is not audible.
Ultrasound is acoustic (sound) energy in the form of waves having a frequency above the human hearing range. The highest frequency that the human ear can detect is approximately 20 thousand cycles per second (20,000 Hz). This is where the sonic range ends, and where the ultrasonic range begins. Ultrasound is used in electronic, navigational, industrial, and security applications. It is also used in medicine to view internal organs of the body.
Hence, the ultrasonic frequency range is above 20,000 Hz.