You would exclude rocks and the nutrients they provide if you were creating an example of an ecosystem. An ecosystem is a community of living organisms, such as plants and animals, and their physical environment. This includes the air, water, and soil, as well as the interactions between the different species and their habitats. Rocks and the nutrients they provide are not part of the living component of an ecosystem, and therefore would not be included in an example of an ecosystem. The correct answer is option B, rocks and the nutrients they provide.