When You Enter a Darkened Area After Being in Bright

When you enter a darkened area after being in bright light, it takes your eyes some time to adjust to the difference in illumination levels. This is because

A) the photopigment bleached by the brighter light takes some time to regenerate.
B) it takes time for your eyes to metabolize vitamin A and provide a new source of photopigment.
C) your eyes need time to decrease the large amounts of photopigment in your retina that were created when you were in the bright light.
D) your photoreceptors are fatigued and need time to rest so that they can recover from the excessive neural activity caused by being outside.
E) the photopigment takes time to be rebleached in the dim lighting.