"AP Psychology – 2025 Biological Bases of Behavior Practice Test: The Complete All-in-One Study Guide to Exam Success!"

Dopamine is a crucial neurotransmitter in the brain that has significant roles in both movement and the experience of pleasure, which is why the correct choice is centered on these two functions. It is particularly well-known for its involvement in the brain's reward pathways, where it facilitates the feeling of pleasure and reinforces behaviors that are necessary for survival, such as eating and reproduction. Furthermore, dopamine is essential for coordinating movement and is heavily involved in the control of motor functions. This is highlighted in conditions like Parkinson's disease, where a deficiency of dopamine leads to severe motor impairment.

The other choices, while relating to different neurotransmitters or functions in the brain, do not accurately describe the primary roles of dopamine. For instance, inhibitory neurotransmission and muscle contraction are more associated with other neurotransmitters. Similarly, regulating sleep and arousal is primarily influenced by different neuromodulators, such as serotonin or norepinephrine. Together, these distinctions clarify why movement and pleasure recognition are specifically linked to dopamine.