The change in an organism's surroundings that provides a response is called a stimulus.

Here's a breakdown:

* Stimulus: Any change in the internal or external environment that can be detected by an organism. This could be anything from a change in temperature, light, sound, or even the presence of food or a predator.

* Response: The action or reaction of an organism to a stimulus. This could be a physical movement, a change in behavior, or a physiological adjustment.

Example:

* Stimulus: A bright light shines in your eyes.

* Response: You blink or squint to reduce the amount of light entering your eyes.

Let me know if you'd like more examples!