Which of the following terms refers to a structure designed to protect against erosion?

The term that refers to a structure designed to protect against erosion is "rip rap." Rip rap consists of large stones placed along coastlines, riverbanks, or shorelines to absorb and deflect wave energy, thereby reducing the impact of water on susceptible areas and preventing erosion.

Rip rap functions effectively as a natural barrier, for example, by stabilizing the shoreline and acting as a buffer against storms and high waves. It plays a critical role in coastal management practices aimed at protecting infrastructure and maintaining natural coastal ecosystems.

In contrast, reclamation pertains to land recovery from water bodies; afforestation involves planting trees to restore forests; and coastal sand dunes are natural formations created by wind-deposited sand, which can provide some protection against erosion but are not engineered structures like rip rap.