The Reason for a "Blind Spot" in the Visual Field

The reason for a "blind spot" in the visual field is that

A) rods are less sensitive to light than are cones.
B) blood vessels collect together and enter the eye at the blind spot.
C) the lens cannot focus all of the visual field onto the retina.
D) retinal cells die with age and overuse, resulting in blind spots.
E) there are no photoreceptors in the retina where the axons exit the eye.