Answer:
A. People cut down the trees in a forest, leaving less habitat for squirrels.
Explanation:
A large percentage of the depletion of an ecosystem can be attributed to anthropogenic or human activities. Ecosystems are naturally known to support or inhabit life. For example, many trees in an ecosystem are homes to living organisms such as birds, insects, snakes etc.
However, according to this question, an exemplary description of how humans can decrease an ecosystem's ability to support life is when "people cut down the trees in a forest, leaving less habitat for squirrels". This act will decrease the forest's ability to support life.
