Biology

The correct answer is:

D.All the communities in an area and the physical environment.

An ecosystem includes not just the different populations (communities) of organisms in a given area, but also the abiotic (non-living) components of that area, such as soil, water, air, temperature, and sunlight. The ecosystem encompasses the interactions between the living organisms (plants, animals, microorganisms) and their physical environment, and how energy and nutrients flow through the system.

Here’s why the other options don't fit:

A.One individual of...