A fundamental concept of ecology is that living
organisms
(1) are independent and do not interact with
each other or with the physical environment
(2) do not interact with other living organisms, but
do interact with the physical environment
(3) interact with each other, but do not interact
with the physical environment
(4) interact with other living organisms and
interact with the physical environment

(4) interact with other living organisms and interact with the physical environment.

Explanation:

Ecology is a branch of biology in which we study about relationship that is present between living organisms with their environment. Alexander von Humboldt is the first person who study the relationship between organisms and environment. He is also called father of ecology due to its contributions to this field. Ecology consist of 5 levels i. e. organism, population, community, ecosystem, and biosphere.