Answer: The correct answer is "sonar".
Step-by-step explanation:
Sonar: It is sound navigation ranging. It uses sound propagation to navigate the object under the surface of the water. This technique is used by the ships. It consists of transmitter and receiver.
It is used to measure the depth of the water by using sound wave. It sends the sound wave by the transmitter and then it reflects back and then, the reflected sound wave is received by the receiver. Then, this distance is calculated to measure the depth of the sea or detect the object under water.
Therefore, the process of using sound waves underwater to measure distance is called Sonar. The correct option is (B).