Anything in the environment that affects the behavior of an organism is called a stimulus.

Here's why:

* Stimulus: A stimulus is any change in the environment that can be detected by an organism and triggers a response. This can include things like:

* Physical stimuli: Light, sound, temperature, touch, chemicals

* Social stimuli: Interactions with other organisms, such as mating calls or aggression

* Internal stimuli: Hunger, thirst, pain

Let me know if you have any other questions!