What effects does caffeine have on the central nervous system when consumed in moderation?

Caffeine is widely recognized for its stimulating effects on the central nervous system. When consumed in moderation, it primarily acts as a stimulant that enhances wakefulness and increases mental alertness. This is achieved by blocking the action of adenosine, a neurotransmitter that promotes sleep and relaxation. As a result, individuals often experience improved focus, reduced fatigue, and enhanced cognitive function.

The stimulation of the central nervous system leads to a heightened state of alertness, making caffeine a popular choice among those looking to boost their energy and sharpen their concentration, especially in situations requiring extended attention or during periods of fatigue. This mechanism illustrates why the selected answer is correct, highlighting the positive effects caffeine has on mental performance and vigilance.