The region of the vertebrate eye, where the optic nerve passes out of the retina, is called the (a) fovea (b) iris (c) blind spot (d) optic chiasma.

Blind spot is the part where the optic nerve passes out of the retina. Photoreceptors are absent in this region. Blind spot is a small portion of the visual field of each eye that corresponds to the position of the optic disc (also known as the optic nerve head) within the retina. There are no photoreceptors (i.e., rods or cones) in the optic disc, and, therefore, there is no image detection in this area. So, the correct answer is option C.