Which of the following are examples of sedatives?

The correct choice includes alcohol, barbiturates, and benzodiazepines as examples of sedatives because these substances are known to depress the central nervous system. Sedatives are primarily used to induce relaxation, reduce anxiety, and promote sleep.

Alcohol is widely recognized for its sedative effects, as it can slow down brain activity and produce a calming effect. Barbiturates and benzodiazepines are also central nervous system depressants used medically to treat anxiety, insomnia, and other conditions by enhancing the effects of a neurotransmitter called gamma-aminobutyric acid (GABA), which further contributes to their sedative properties. The combination of these three substances reflects the pharmacological classification of sedatives, illustrating their common function in reducing arousal and promoting sedation.

The other options do not fit the criteria for sedatives. Caffeine and nicotine, for example, are stimulants that increase alertness rather than induce sedation. Similarly, PCP, methamphetamine, and LSD are classified as hallucinogens and stimulants, which act to enhance excitability rather than promote relaxation or sleep. Opioids are primarily pain relievers that can have sedative properties, but stimulants and antidepressants do not serve the purpose of sedation in the