An oceanographic vessel is mapping a section of the ocean floor stretching for tens of kilometers in all directions. The seafloor is extremely flat, with a slope of less than one degree, and the water depth is about 4500 meters. The area being mapped is most likely a(n) .

Abyssal plain

Explanation: Abyssal plain is an underwater plain on the deep ocean floor, They are vast, flat, sediment-covered area of the deep ocean floor covering tens of miles and over 6000km deep. The continental shelf is an areas of the continent submerged under shallow water. The continental rise is found between the continental slope and the Abyssal plain. The Abyssal plain are depositional surfaces on the sea floor housing sediments such as wind-blown dust, volcanic ash and so on.

answer; clear and present danger test;