Final answer:
Caffeine enhances attention and physical performance, supporting enhanced alertness and reduced perceived exertion during tasks. It works as a CNS stimulant by blocking adenosine receptors, increasing energy metabolism, and can impair sleep quality at high doses.
Step-by-step explanation:
Caffeine is a central nervous system (CNS) stimulant widely consumed around the world, known for its ability to enhance alertness and physical performance. The effects of caffeine include improved athletic performance in aerobic and anaerobic conditions, such as improved muscular strength, power, and endurance. Furthermore, caffeine intake prior to exercise has been associated with reduced perceived exertion and increased energy metabolism, which could lead to enhanced attention and vigilance during tasks, thereby supporting option D) Enhanced attention.
Regarding sleep, caffeine is a known adenosine antagonist, which inhibits the action of the neurotransmitter that promotes sleepiness, thereby increasing wakefulness and potentially impairing sleep quality when consumed in excess. Contrary to enhancing sleep quality, excessive caffeine can lead to insomnia and increased anxiety, emphasizing the need for careful consumption in regard to sleep health.