Choose the option that represents an example of a stimulant.

Caffeine is indeed an example of a stimulant because it works by increasing the activity of certain neurotransmitters in the brain, leading to heightened alertness and energy. It mainly affects the central nervous system and can improve focus and reduce fatigue, which are common characteristics of stimulant substances.

In contrast, oxycodone is an opioid pain medication that has sedative effects, alcohol is a depressant that slows down brain functions and can impair judgment and coordination, and LSD is a hallucinogenic drug that alters perception and mood rather than stimulating the central nervous system.