The left pupil of a patient fails to accommodate.This finding may reflect an abnormality in which cranial nerve?

A) CN III
B) CN V
C) CN VIII
D) CN X

CN III, also known as the oculomotor nerve, is responsible for controlling the movements of the eye muscles that control the pupil size and accommodation. A lesion or abnormality in CN III can lead to a failure of the pupil to constrict or enlarge appropriately in response to light and accommodation.