A reflex occurs the iris of the human eye in response to changes in light levels - describe how these changes occur, referring to the changes in light level in your answer.

I would most likely present a figure of a dilated & undilated pupal and hopefully this will begin their thought process.
To receive full marks for this answer, I will be looking for the below points:•  pupils dilate in low light levels because• circular muscles (in iris) relax • (and) radial muscles contract