By using sound waves, signals allow oceanographers to determine ocean depth.

Sonar.

By using sound waves, signals allow oceanographers to determine ocean depth. 

Sonar is a device that uses long, medium or short sound waves for navigation, communication, detection, positioning, tracking, and classification of mobile and immobile objects submerged, located on the surface of the liquid or in the air.

Your answer is d. silli hope this ! : ) i left an explanation down below if you need it: a sill forms when hot magma squeezes between layers of rock to form a hardened sheet of rock. a sill is basically a tabular sheet intrusion between old layers of sedimentary rock, volcanic beds, or in the direction of foliation inherent in metamorphic rock. the word sill means a concordant intrusive sheet.

All the planets