Which coastal feature is primarily formed through wave action and erosion?

The coastal feature that is primarily formed through wave action and erosion is the headland. Headlands typically form in areas where there are more resistant rock types present, which withstand the process of erosion better than the surrounding softer rock. As the waves crash against the rock face, they gradually remove material through processes such as hydraulic action, abrasion, and corrosion. Over time, this constant erosion leads to the formation of a headland, which protrudes into the sea.

On the other hand, a beach is primarily formed by the deposition of sediments rather than erosion. Coastal cliffs also undergo erosion, but they are not as prominently identified as a landform shaped by wave action alone in the same manner. Sand dunes are formed by wind activity and the accumulation of sand rather than by wave action and erosion. Therefore, the headland stands out as the correct answer, emphasizing its development through the dynamic interactions between waves and the Earth's geology.