The correct option is C Earthquake prediction
Ultrasonic sound is sound with a high frequency of greater than 20 kHz. It finds its applications in medical procedures like echocardiography (monitoring heart function using ultrasound echo), breaking stones in kidneys, as well as in other fields such as estimating the depths of water bodies like seas, and oceans, etc. using SONAR.
However, ultrasound is not used in predicting the occurrence of earthquakes, or volcanic eruptions, instead, infrasonic sound (frequency <20 Hz) is used.