The Reason That the Blind Spot Is Not Perceived as a Black

The reason that the blind spot is not perceived as a black hole in our visual field is

A) that the optic nerve connects at the blind spot, and it is where we have the highest concentration of cones and rods.
B) that the blind spot doesn't really exist.
C) because we usually have both eyes open, and each eye provides a slightly different view.
D) that the optic nerve connects at the blind spot and it contains cones to allow us to see colour.