Which of the following is classified as a depressant drug?

The classification of alcohol as a depressant drug is rooted in its effects on the central nervous system. Depressants are substances that slow down the functioning of the brain and body, often leading to relaxation, a reduction in anxiety, and impaired motor coordination. Alcohol, when consumed, acts on neurotransmitters in the brain, particularly gamma-aminobutyric acid (GABA), enhancing its effects and producing a calming effect.

Marijuana, while it can have sedative properties for some users, is categorized more accurately as a psychoactive substance that can cause both depressant and stimulant effects, depending on the strain and the user. Caffeine is a stimulant that increases alertness and can cause restlessness and anxiety. Cocaine is also a stimulant known for increasing energy and euphoria.

In summary, alcohol's well-documented ability to depress the central nervous system and its association with slowed cognitive and motor functions clearly categorize it as a depressant drug, distinguishing it from the other options listed.