For which of the following purposes, ultrasonic waves are not used?

Correct option is C

1. Ultrasound waves are high-frequency sound waves that can penetrate the body and produce images of soft tissues.

2. The ultrasound machine sends ultrasonic waves into the body, and the echoes are captured to create real-time images.

3. Unlike X-rays, ultrasound does not use harmful radiation, making it safer for repeated use, especially during pregnancy.

4. It is commonly used in obstetrics to monitor the development of a fetus.

5. Ultrasound is also used in cardiology to evaluate heart conditions, in urology for kidney stones, and in musculoskeletal medicine to check for soft tissue injuries.

• Bats to find their prey : This is a correct use of ultrasonic waves, as bats use echolocation to detect prey and navigate.

• To find the depth of the ocean floor by ship : This is another correct use of ultrasonic waves in sonar technology to measure the ocean floor's depth.

• To detect aircraft in the sky : Aircraft detection is performed using radar, which uses radio waves, not ultrasonic waves.