Here's why:

* Stimulus: Anything that causes a reaction in an organism. This could be a sound, light, touch, smell, taste, or even internal changes like a change in blood sugar.

* Response: The way an organism reacts to a stimulus. Responses can be simple, like withdrawing a hand from a hot stove, or complex, like learning a new language.

Examples:

* Stimulus: A loud noise

* Response: You jump or flinch

* Stimulus: The smell of freshly baked cookies

* Response: Your mouth starts to water

Let me know if you have any other questions!