Respuesta :
C- the submarine could be rising towards the surface
Answer:
A- The signals could be reflecting off of objects above the ocean floor is the answer.
Explanation:
According to National Ocean Service, a sonar is a helpful tool for exploring and mapping the ocean. They are used to develop nautical charts, locate underwater hazards to navigation, search for and map objects on the seafloor such as shipwrecks, and map the seafloor itself. There are two types: active (emit an acoustic signal) and passive (which receive that signal.)