Final answer:
The least inclusive level of organization in the options provided is the atom, which is the basic unit of a chemical element and the smallest level of biological organization.
Step-by-step explanation:
The hierarchy of biological organization from the most to the least inclusive can be represented as biosphere, ecosystem, community, population, organism, organ, tissue, cell, organelle, molecule, and atom. In the sequence provided, the least inclusive level of organization is the atom.
An atom is the basic unit of a chemical element, and it is the smallest level of organization that still retains the properties of the element. Moving up the hierarchy, atoms combine to form molecules, which can combine again to form organelles, the substructures within cells. Cells then make up tissues, tissues make up organs, organs make up organ systems, and organ systems make up organisms.
Populations consist of organisms of the same species living in an area, communities comprise different populations interacting, ecosystems include communities and their physical environments, and the biosphere encompasses all living things on Earth.