When entering a dark room, the pupil of your eyes do what?

Question

When entering a dark room, the pupil of your eyes do what?

Answer 1

The pupil expands (opens wider) to allow more light into the eye.

Answer 2

expand to allow more light, or the red light.

Answer 3

They dilate, so that more light is let into the eye, making for better vision.  

Conversely, the pupils shrink when entering very bright light to shield the optic nerve from excessive light exposure.

Answer 4

Dilate to let more light in so you can see.