An ocean basin is best described as?

• A. A geologic basin covered by seawater, including land underneath it.
• B. A dry inland basin with no water.
• C. A shallow pond in a desert.
• D. A mountain valley filled with freshwater only.

Answer: (A)

An ocean basin is a large depression in the Earth’s crust that collects seawater, so it includes the water and the land beneath it. This means the basin isn’t just a water body floating above bare rock—it extends over the submerged land and crust that define its edges, like the continental shelf and adjacent ocean floor. The other ideas describe environments that don’t fit the ocean basin concept: a dry inland basin has no seawater, a shallow desert pond is small and not part of the ocean system, and a mountain valley filled with freshwater isn’t an ocean basin. So describing an ocean basin as a geologic basin covered by seawater, including the land underneath it, captures both the water and the underlying land that define the feature.