Which of the following substances is categorized as a behavioral stimulant?

Amphetamines are considered behavioral stimulants because they primarily increase the activity of certain neurotransmitters in the brain, particularly dopamine and norepinephrine. This heightened activity enhances alertness, attention, and energy levels, leading to increased physical and mental performance. Behavioral stimulants are known for their ability to elevate mood and reduce feelings of fatigue or lethargy.

In contrast, the other substances mentioned have different classifications: alcohol is a depressant that slows down brain activity; marijuana acts as a mild hallucinogen and its effects can be either relaxing or stimulating depending on the strain; and barbiturates are also depressants, used primarily for their sedative effects. Understanding these distinctions is crucial in recognizing how different substances impact behavior and mental processes.