Which of the following is not a major division of the ocean floors?

These are deep valleys, some comparable to the Grand Canyon of the Colorado river. They are sometimes found cutting across the continental shelves and slopes, often extending from the mouths of large rivers. These are considered a minor relief feature. Four major divisions can easily be identified on the ocean floor—(i) the continental shelf, (ii) the continental slope, (iii) the continental rise, (iv) the abyssal plain. Besides these, there are many associated features—ridges, hills, seamounts, guyots, trenches, canyons, sleeps, fracture zones, island arcs, atolls, coral reefs, submerged volcanoes and sea-scarps.