Most of the ocean floor is made up of . A. deep-ocean trenches (8 to 11 km below sea level) B. abyssal plains (4 to 5 km below sea level) C. mid-ocean ridges (less than 2.5 km below sea level) D. Elevations of the sea floor are nearly uniformly distributed from sea level to 11 km depth.

Option (B)

Explanation:

Abyssal plains are underwater features that forms more than 50% of the total ocean floor. It generally lies at a depth ranging from 3 to 6 km below the mean sea level, which mainly covers the region between the mid oceanic ridges and the continental rise. It is comprised of numerous sediments and the rocks formed here mainly basaltic igneous rocks. This abyssal plain region is not uniformly horizontal. They are irregular and rough surfaces.

Thus, the majority of the seafloor is comprised of the abyssal plains.

Therefore, the correct answer is option (B).

C. mid-ocean ridges (less than 2.5 km below sea level)

Explanation: