Which of the following describes a community A. a lifeless desert of rocks, sand, and high temperatures B. a hole in which a ground squirrel lives C. a forest of birds D. The ocean

I would say the ocean. In the ocean, the fish and plants are a community, and if one weren't there, no one would survive.

C. A forest of birds, because in a forest it is a variety of other organisms birds in this case are primary. They have to take care of each other, build nest, and take care of their children. They are community itself full of predators