Which of the following is an example of a biotic factor in an ecosystem?

In an ecosystem, biotic factors refer to the living components that influence and interact with the environment. Plants represent a fundamental biotic factor because they are living organisms that play crucial roles in ecosystems, such as providing food, oxygen, and habitat for various species, including herbivores and the predators that rely on them. Moreover, plants contribute to ecosystem functions like photosynthesis and nutrient cycling, showcasing their integral role in maintaining ecological balance.

In contrast, the other options refer to abiotic factors, which are non-living elements that also affect ecosystems. Soil composition refers to the mineral and organic materials found in the earth, while water temperature affects the physical and chemical processes in aquatic environments but is not a living factor. Rock formations are geological structures that shape landscapes but do not have any living characteristics. Hence, recognizing plants as the only biotic factor in this question emphasizes their importance in ecological interactions and environmental health.