How are ocean waves primarily formed?

Ocean waves are primarily formed by the friction between wind and the ocean surface. As wind blows across the water, it transfers energy to the surface, causing the water to move in waves. The speed of the wind, its duration, and the distance it blows over the water (called fetch) all contribute to the size and strength of the waves that are generated. This process is a fundamental aspect of ocean dynamics and is crucial for understanding various marine and coastal phenomena.

The other options represent processes that can influence the ocean but do not primarily generate waves. For example, underwater volcanic activity can create localized disturbances in the water, such as tsunamis or thermal waves, but it is not the main mechanism responsible for the everyday waves seen on the ocean's surface. Similarly, tectonic plate shifts can lead to seismic events that generate tsunamis, but again, they do not account for the formation of regular ocean waves. Finally, temperature differences in the water can lead to currents and other movements within the ocean but do not directly cause wave formation as wind does.