Concept:The shallow underwater extension of land along the coast is known as the continental shelf.
Explanation:The sea floor near the land is not deep immediately.
It slopes gently seaward over the submerged edge of the continent.
This gently sloping, shallow part of the sea adjoining the coast is called the continental shelf.
Continental shelves are usually rich in marine resources.
The continental slope is the steeper descent beyond the shelf, not the shallow coastal part.
An oceanic island is a landmass surrounded entirely by ocean.
An oceanic plateau is a large, relatively flat elevated area on the deep ocean floor.
Therefore, the shallow part of the sea adjoining the coast is not the slope, island, or plateau.
Answer:A. continental shelf