Which of the following is classified as a narcotic drug?

Fentanyl is classified as a narcotic drug because it is a potent synthetic opioid used medically for pain relief and is known for its effectiveness in treating severe pain. Its classification as a narcotic stems from its ability to bind to opioid receptors in the brain, leading to pain relief as well as potential for euphoria, which contributes to its potential for abuse and addiction.

In contrast, LSD (lysergic acid diethylamide) is a hallucinogenic drug that affects serotonin receptors and does not fit the category of narcotics. Psilocybin, found in certain mushrooms, is also a hallucinogen rather than a narcotic. Lastly, MDMA (commonly known as ecstasy) is classified as an empathogen and stimulant, which also does not fall under the narcotic category. Understanding these classifications is crucial for distinguishing between different types of drugs and their effects, uses, and potential for abuse.