Final answer:
Life is an emergent property that arises at the cellular level but is most fully expressed at the organismal level, where all systems interact to maintain life.
Step-by-step explanation:
Life is considered an emergent property that becomes apparent at a certain level of biological organization. Looking at the hierarchy of biological organization, life manifests at the cellular level since the cell is the basic unit of life. However, as we proceed through the levels of tissues, organs, and organ systems, these collectively make up an organism, where life is not just present but exhibits complex, physiologically functional interactions. Thus, while life begins to emerge at the cellular level, it is at the organismal level where the complexity and capacity for life are fully realized. In summary, life is an emergent property that is most evidently expressed at the organismal level.