What does the word ecosystem refer to?
all the animal and plant species within a geographical area
classification for a broad type of habitat, such as savanna or tropical forest
group of interacting populations in a defined place and the nonliving factors that affect
them
all the members of one species living in one place and time

group of interacting populations in a defined place and the nonliving factors that affect  them

Explanation:

An ecosystem is a group of interacting populations in a defined place and the nonliving factors that affect  them.

An ecosystem can also be a natural unit composed of living and nonliving components whose interactions result in a stable self-supporting system. Ecosystems are generally categorized as either aquatic or terrestrial.

just here for the other one bc they put up with u