Which of the following best defines ecology?

Ecology is best defined as "the scientific study of interactions among organisms and between them and their environment." This comprehensive definition captures the essence of ecology, emphasizing not just the relationships between various living organisms but also how these organisms interact with their physical surroundings.

Understanding these interactions is crucial for a deeper insight into ecosystem dynamics, biodiversity, and the impact of environmental changes. These interactions can include various forms such as predation, competition, symbiosis, and the influence of abiotic factors—like climate and soil conditions—on living organisms.

The other options do not encompass the complete scope of ecology. Focusing solely on living organisms ignores their relationships with the environment that are vital to ecological studies. The examination of nonliving factors in a habitat is a subset of ecological study and does not capture the full range of interactions. Lastly, while studying energy flow is an important aspect of ecology, it is just one facet of the broader interactions within ecosystems. Thus, the selected answer encompasses the entirety of ecological study, making it the most accurate definition.