The iris reflex?

a) protects the retina from too much light



b) lets the retina detect coloured light



c) changes the shape of the lens



d) stops the eyeball from drying out



please do give an answer unless you are 100% sure.

this question is to do with science.

thanks

The iris reflex?
A- The natural adjustment in the size of the pupils is called the iris reflex, which is extremely rapid. This iris reflex action automatically adjusts the pupil when you go from a darkened area to a well lit area, or, from a well lit area to a darkened one.



When the pupil contracts, it becomes too small and the light spot is covered, then the pupil dilates and gets to the size where the light spot can enter the eye, so the pupil will contract again, and so on. The delay in the pupil response to the light being on or off determines the period of these oscillations. This pupil cycling is important in medical diagnosis, since some nerve deffects influence the way the pupil oscillates, and the range of the pupil threshold area (determined by the position of the light spot) for which it oscillates.