Which term is best described as a flat expanse of ocean floor?

A. continental shelf

B. abyssal plains

C. guyots

D. deep sea trenches

The correct answer is B. abyssal plains.

The abyssal plain is a flat seafloor area at a depth between 3,000 and 6,000 m generally adjacent to a continent. Those plains are most common in the Atlantic Ocean, irregular in outline but generally elongate along continental margins. Some of them are huge hundreds of kilometers wide and thousands of kilometers long.

I think the correct answer from the choices listed above is option B. Abyssal plains are the vast flat lands beyond the continental shelf that cover almost half of the ocean floor, flat expanses of sediment covering ocean floor. Hope this answers the question. Have a nice day.