Describe some of the problems faced by benthic organisms in the ocean

The benthic organism is an organism that lives on, in or near the seafloor. This also helps the environment and marine life by providing structure, alter water currents, and stabilize shorelines, hard substrate settlement. Some recycle nutrients and improve water quality. An animal of a large group distinguished by the possession of a backbone or spinal column, including mammals, birds, reptiles, amphibians, and fishes. 

the answer for this question would be d. glaciers