Where does the optic nerve cross the midline?

a. optic chiasm

b. primary visual cortex

c. corpus callosum

d. midbrain?

The answer to this question would be: a. optic chiasm

The optic nerve will be crossed in optic chiasm. Only a part of the optic nerve is crossing the midline. So, if there is a damage in the nerve after crossing, the visual loss will not only appear in one eye but half of both eye. Damage in right visual cortex will cause the left and right eye losing their half (left part) of their visual field.