Describe the role of pressure in determining sound speed.

The correct choice highlights that increased pressure compresses water, which in turn leads to an increase in sound speed. In the ocean, sound travels faster in denser medium, and as pressure increases with depth, the density of water increases due to the compression effects. This increased density combined with the effects of temperature and salinity leads to a higher sound speed in deeper layers of water.

In oceanographic acoustics, understanding how sound speed varies with environmental factors is crucial for applications such as sonar operations, underwater communication, and marine research. As pressure increases, it not only enhances density but also affects other properties influencing sound propagation.

While it might seem logical that pressure could have no effect or could decrease sound speed, the principles of fluid dynamics confirm that as fluids (like seawater) are subjected to more pressure, they become more compact, leading to improved sound transmission.