Which of the following substances is classified as a stimulant?

MDMA, also known as ecstasy, is classified as a stimulant because it primarily increases the activity of neurotransmitters in the brain, specifically serotonin, dopamine, and norepinephrine. This increased activity leads to heightened energy, alertness, and euphoria, which are characteristic effects of stimulant substances. Unlike depressants such as alcohol, which slow down brain function and body processes, or hallucinogens like LSD and cannabis that alter perception and consciousness without the stimulant effects, MDMA is explicitly recognized for its energizing and mood-enhancing properties. This classification is essential in understanding how different substances affect behavior and physiological responses, aiding in the development of appropriate treatment and intervention strategies in alcohol and drugs counseling contexts.