Answer:
C - Abyssal zone contains the remains of dead organisms and other matter that has settled to the ocean floor.
Step-by-step explanation:
The abyssal zone is at the depth of 3000 m to 6000 m in the ocean and it makes up 83% of ocean. It also covers approximately 60% of the earth. There is no light in this zone which means lack of oxygen producing plants.
Furthermore, organism die due to lack of oxygen if they roam this zone and end up on the seafloor. It is also rich in nutrients and minerals such as phosphorus, silica, nitrogen, and nutrients salts due to death of organic material in large amounts.