Final answer:
Hydroxyamphetamine 1% stimulates the sympathetic nervous system and leads to pupil dilation or mydriasis by binding to receptors, similar to the body's natural fight-or-flight response.
Step-by-step explanation:
Hydroxyamphetamine 1% is an ophthalmic agent used to stimulate certain receptors in the eye. Specifically, it stimulates the sympathetic nervous system when applied topically, which leads to pupil dilation or mydriasis. This effect is similar to how norepinephrine, a neurotransmitter, binds to the adrenergic receptors in the radial fibers of the iris smooth muscle, thus causing the pupils to dilate. This process mimics the body's natural fight-or-flight response, where pupil dilation allows more light into the eye and enhances visual capability in a high-alert situation.
The sympathetic nervous system is also responsible for a variety of other body responses, such as an increase in heart rate and inhibition of digestion, as part of the fight-or-flight response. However, for the question at hand, Hydroxyamphetamine 1% mainly affects the radial muscle of the iris and leads to pupil dilation. Therefore, the answer to the question is A) Pupil dilation.