Q: What produces sound waves that travel outward in all directions in water?


Read this paragraph and choose the correct option from the provided answers:

During World War II, battleships and submarines carried echo sounders. Their goal was to locate enemy submarines ( Figure below ). Echo sounders produce sound waves that travel outward in all directions. The sound waves bounce off the nearest object and then return to the ship. Scientists know the speed of sound in seawater. They then can calculate the distance to the object that the sound wave hit. Most of these sound waves did not hit submarines. They instead were used to map the ocean floor.

 Choices:

- echo chamber

- ultrasound machines

- amplifiers

- echo sounders


A:
echo sounders