An ecosystem includes ... A. only the non-living parts of the community. B. only the living members of the community. C. both the living, and non-living parts of the community.

I think the correct answer is A but i'm not really sure.

An ecosystem includes both the nonliving and living part of the community because in the Marines a. k. a. Salt water the algae eats the dead organisms in the water so without nonliving organism The decomposers wouldn't be able to decompose anything so the answer is C.