Biology

The correct answer is:

B. An area of cold climate and communities of similar species.

An ecosystem includes both living organisms (communities of different species) and the abiotic factors (non-living elements like climate, water, soil, and sunlight) in a particular area. The example of "an area of cold climate and communities of similar species" describes not just the living organisms, but also the environmental factors that make up an ecosystem.

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

A. One elk: This is an individual, not an ecosystem....