answer: ecosystem
why: an ecosystem is all the living (biotic) and non-living (abiotic) things living and depending on each other. example: pond. fish, frogs, and alage living in water and rocks.
All the other levels are broken down and divided versions of this. A community is all the living things in an area. An individual is a single organism, and a population is all the animals of just one specices in an area. An ecosystem is all of these put together.