Concept:The shallow underwater extension of a continent, closest to the land, is the continental shelf.
Explanation:The ocean basin begins at the edge of the continent.
The first zone encountered is the continental shelf.
It is a gently sloping, shallow submerged plain attached to the land.
This makes it the nearest part of the ocean basin to the continent.
Moving further seaward, the next features are the continental slope and then the deep ocean floor.
Therefore, the correct option is continental shelf.
Answer:C. continental shelf