Final answer:
The pupil is controlled by the Autonomic Nervous System.
Step-by-step explanation:
The autonomic nervous system is responsible for controlling involuntary movements in the body. The movements of the pupil are controlled by the autonomic nervous system. When the sympathetic division of the autonomic nervous system is activated, it causes the pupil to dilate, allowing more light to enter the eye. When the parasympathetic division is activated, it causes the pupil to constrict, limiting the amount of light entering the eye. Therefore, the correct answer is a. Pupil.