Which of the following drugs is categorized as a stimulant?

Dexedrine is categorized as a stimulant because it contains dextroamphetamine, which increases the levels of certain neurotransmitters in the brain, particularly dopamine and norepinephrine. This results in enhanced alertness, attention, and energy levels, characteristic effects of stimulants. Dexedrine is commonly prescribed for Attention Deficit Hyperactivity Disorder (ADHD) and narcolepsy, where an increase in focus and wakefulness is beneficial.

The other drugs listed are classified differently. Nembutal is a barbiturate, which acts as a depressant on the central nervous system, leading to sedation and relaxation. Xanax is an anti-anxiety medication that falls under the category of benzodiazepines, also serving to depress the central nervous system. THC, the active component of cannabis, is primarily associated with psychoactive and relaxing effects rather than stimulant properties. Understanding the classification of these substances is crucial for recognizing their effects and potential for misuse or dependence.