Which of the following describes a stimulant?

A stimulant is characterized by its ability to increase the activity of the central nervous system (CNS). When a substance causes CNS stimulation, it typically enhances alertness, attention, and energy levels. This can lead to increased heart rate and heightened sensory perception, which are hallmark effects of stimulants.

In contrast, substances that depress the CNS typically slow down brain function and overall bodily functions, resulting in effects such as sedation or relaxation, which are not related to stimulant properties. Similarly, substances that induce relaxation and sedation or are exclusively used for pain relief do not align with the defining characteristics of stimulants, as they instead focus on calming effects or analgesic properties. Thus, the correct description of a stimulant is inherently linked to its stimulating effect on the CNS.