Which of the following best describes the concept of 'habitat'?

The concept of 'habitat' is best described as the natural environment where an organism lives. This definition encompasses all the elements and conditions that are present in that environment, including the physical surroundings, the availability of food and water, and the presence of other organisms. A habitat provides the necessary resources and conditions that support the survival, reproduction, and growth of a particular species.

The other options are related but do not accurately capture the essence of what a habitat is. For instance, describing habitat in terms of the role an animal plays in its ecosystem focuses more on the organism's function within an ecological context, rather than its physical living space. The option that refers to the combination of living and non-living factors describes an ecosystem rather than a specific habitat. Lastly, measuring an organism's fitness pertains to its ability to survive and reproduce in its environment, which is influenced by its habitat but does not define what the habitat itself is. Thus, the best definition aligns with the idea of habitat as the specific place where an organism resides.