When a person enters a dark room from bright light he is not able to see clearly for a little while because the?

A. Eye is unable to adjust itself immediately
B. Retina becomes insensitive momentarily
C. Iris is unable to dilate the pupil immediately
D. Distance between the lens and retina take time to adjust
 
The amount of light entering the eye through pupil is controlled by iris. But this adjustment takes some time. Our eyes cannot see everything clearly when we enter a dark room from a bright light. The reason for this is that in bright light the size of pupil of our eye is small. When we enter the dark room, due to small size of pupil, very little light enters our eyes. But after some time, the pupil expands and we become able to see things as more light enter our eyes.