Which statement is true regarding active sonar?

Active sonar works by emitting sound waves into the water and then listening for the echoes that return after bouncing off objects such as submarines or the seafloor. This technology allows for the detection and ranging of objects in the underwater environment. The process helps to determine the distance, size, and possibly even the shape of underwater objects by analyzing the time it takes for the sound waves to return.

In contrast, other options describe different methods or limitations that do not apply to active sonar itself. For instance, passive detection relies entirely on listening to environmental noises without emitting any sound waves, which is not how active sonar operates. Additionally, while active sonar can indeed be used in shallow waters, it is not restricted to that environment; it is also effective in deep water. Similarly, active sonar can be deployed from various platforms, including ships and buoys, not just submarines. Thus, the statement about emitting sound waves and listening for their return accurately characterizes the functioning of active sonar.