What sentence from the passage best describes the main idea? Living and Nonliving Things in an Ecosystem

An ecosystem can be characterized by its living and nonliving things. An ecosystem is a community of living and nonliving things that interact with one another. Living and nonliving things in an ecosystem can affect each other. Living things include plants, animals, bacteria, and fungi. Living things are made up of one or more microscopic parts called cells. Nonliving things include rainfall, temperature, sunlight, water, soil, rocks, and air.
The living and nonliving things in an ecosystem exist together. They impact one another. The nonliving things are important. They help determine what kinds of organisms can survive. The nonliving things help plants and animals survive. For plants, important nonliving things include the kind of soil and the amount of sunlight and water available. For animals, important nonliving things include temperature, water, and oxygen in the air. Nonliving things that can provide shelter for animals can also affect animal life. For example, some animals may find shelter by burrowing in the ground. Other animals may live in caves or between rocks.
Living things can also impact the nonliving things of an ecosystem. For example, plants add oxygen to the atmosphere. Worms living in the ground mix and break up the soil. Algae growing in a lake can reduce the amount of sunlight reaching the bottom of the lake. There are other ways living things can help an ecosystem. Can you think of other ways living things can help nonliving components