Which of the following would be an example of a central nervous system depressant?

Ethanol is classified as a central nervous system depressant because it slows down brain activity and decreases overall neural functioning. When consumed, it enhances the effects of the neurotransmitter gamma-aminobutyric acid (GABA), which leads to sedative effects, decreased anxiety, and impaired motor functions. This is why ethanol is commonly associated with relaxed sensations, reduced inhibitions, and in higher doses, potential sedation or even unconsciousness.

In contrast, cocaine, amphetamines, and LSD have stimulating or hallucinogenic effects. Cocaine and amphetamines are stimulants that increase brain activity, leading to heightened alertness and energy. LSD, a hallucinogenic substance, alters perception and mood without the depressant effect typical of substances like ethanol. Therefore, ethanol stands out as the example of a central nervous system depressant in this context.