The biosphere is a term used to describe the portion of the Earth where life exists. It includes all living organisms, such as plants, animals, and microorganisms, as well as their interactions with each other and their environment.
Therefore, the correct answer is rocks. Rocks are not living things and do not contribute to the biosphere, although they can provide habitat for living organisms.
In summary, the biosphere includes all living organisms and their interactions with the environment, but does not include non-living things such as rocks.