* Behavior is the way an organism reacts to its environment. This can include both internal (like hunger) and external (like a predator) stimuli.

* Growth is a long-term process of increasing in size or complexity.

* Development is a series of changes that occur over an organism's lifetime, leading to maturity.

* Evolution is a long-term process of change in a population over generations.

Therefore, behavior is the only option that directly involves an organism's response to stimuli.