Final answer:
The drug among the options given that is a narcotic and a pain reliever is 2) heroin. It is an opioid derived from morphine and is known for its strong analgesic properties, but it also has a high potential for addiction.
Step-by-step explanation:
Among the drug options listed, the one that is a narcotic and serves as a pain reliever is heroin. Heroin is an opioid drug derived from opium and chemically modified from morphine. This substance is well-known for its analgesic properties, which means it is used to decrease pain. It does so by binding to opioid receptors in the brain, mimicking the body's natural pain-relief mechanisms; however, heroin is also highly addictive and can lead to drowsiness and loss of consciousness in high doses.
While drugs like LSD (lysergic acid diethylamide) and dexedrine (an amphetamine) may affect perception and energy levels, they are not considered narcotics nor are they used as pain relievers. LSD is a hallucinogen and dexedrine is a stimulant, often referred to as 'speed'. They do not have the analgesic properties of opioid painkillers such as heroin, morphine, or prescription medications like oxycodone and hydrocodone. The answer is option 2.