The sun provides energy to the rest of the ocean ecosystem.
An abiotic factor is also known as a non living organism. Since we now know what abiotic means, we can use process of elimination by considering a simple question; is it living?
Sea urchins are biotic, meaning they are living. Plankton are marine animals, meaning they are living and reside in water or in the ocean. Sharks are definitely living.
That knocks out every answer except for D, or the sun.
Our answer is the sun.
