What happens to the pupil in low light conditions?
It expands to allow more light to enter
The pupil is the opening at the centre of the iris through which light enters the eye. Its size is controlled by two sets of muscles in the iris.
In low (dim) light, the radial dilator muscles contract and the pupil expands (dilates), letting more light reach the retina so that we can see better. In bright light, the circular sphincter muscles contract and the pupil becomes smaller to prevent excess light from entering.
So contraction is the response to bright light, not dim light; the pupil does not stay the same size; and eye colour comes from pigment in the iris, while the pupil itself always appears black.
Hence, the answer is It expands to allow more light to enter.
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