Which of these categories influence pupil size?

Pupil size is significantly influenced by the action of central nervous system (CNS) stimulants. These substances can cause the pupils to dilate, a condition known as mydriasis, as a result of their stimulating effects on the brain and sympathetic nervous system. Stimulants typically increase alertness and may enhance the body’s fight-or-flight response, which can also lead to pupil dilation. Various stimulants, such as amphetamines or cocaine, can cause a noticeable increase in pupil size.

Other categories like vitamins, antibiotics, and hormonal agents do not have a direct or significant impact on pupil size in the same way that CNS stimulants do. Vitamins primarily support overall health and functioning of the body, antibiotics focus on treating infections without affecting pupil dilation directly, and hormonal agents can have complex effects on physiology but are not primarily known for influencing pupil size. Thus, the correct choice highlights the specific impact of CNS stimulants on this physiological response.