Which one of the following is the best description of the term 'ecosystem'?
Explanation
Option (C) is correct because an ecosystem is defined as a functional unit comprising both the biotic community (living organisms) and the abiotic environment (physical surroundings) interacting as a system. Option (a) is the most tempting distractor but is incomplete as it only describes a 'biotic community' without accounting for the essential physical environment. The core concept being tested is the structural definition of an ecosystem, which requires the integration of living organisms with their non-living habitat.