Answer: d. autonomic nervous system
Explanation:
The dilation of the pupil occurs due to the radial muscles. This is controlled by the autonomic nervous system. The autonomic nervous system consists of sympathetic and parasympathetic nervous system. The sympathetic nervous system controls the dilation of pupil whereas the parasympathetic nervous system controls the contraction of pupil.
A dilation response generally involves the widening of the pupil that may be caused by the adrenaline and drugs like cocaine, MDMA, amphetamines, hallucinogens and dissociatives.
