COMT Practice Exam 2025 – Complete Resource for Exam Prep

The autonomic nervous system is the correct answer because it is responsible for controlling involuntary bodily functions, which include the regulation of pupil size and reaction. This system is divided into two main branches: the sympathetic nervous system, which triggers dilation of the pupils to allow more light in during situations that require heightened awareness or 'fight or flight' responses, and the parasympathetic nervous system, which controls constriction of the pupils in relaxed states.

The central nervous system, while it plays a role in processing sensory information and initiating reactions, does not directly control pupil size and reaction as autonomously as the autonomic nervous system. The somatic nervous system is primarily responsible for voluntary movements and does not involve involuntary reflexes such as pupil adjustment. The peripheral nervous system encompasses both the somatic and autonomic systems but does not specifically control pupil size and reaction on its own. Thus, the autonomic nervous system is uniquely tasked with managing these involuntary responses effectively.