The illustration is missing the type of organisms known as decomposers. They break down dead animals and plants and have the vital role in returning the nutrients back into the system, where they can be used once more by the primary producers.
In the illustration:
The primary producers are the phytoplankton.
The primary consumers are the: krill, cod and zooplankton
The secondary consumers are the remaining species that feed on the primary consumers.
I just took the quiz!
Answer and explanation is in a file. Link below. Good luck!
Answer is C i just got this answer on usatestprep
The answer is C) Organisms that can convert the sun's energy into a useable form of energy.
I have a 100 on the quiz in Usa Test Prep
Hope this is correct!