An Echo Sounder Operates by Measuring the Time Required for ________

An echo sounder operates by measuring the time required for ________.

A) a sound pulse travels from a ship to the seafloor and back
B) a laser beam to travels from a ship to the seafloor and back
C) a radar pulse to travel from a ship to the seafloor and back
D) a radar pulse to travel from a satellite in orbit around Earth to the sea surface and back