Question

pigmented, circular muscle in the eye that regulates the size of the pupil
daphne
ivy
lily
iris
violet

Explanation:

The iris is a pigmented, circular muscle in the eye. Its main function is to regulate the size of the pupil. This regulation controls the amount of light entering the eye. Daphne, Ivy, Lily, and Violet are names of plants or flowers and have no relation to the eye - related structure described.

Answer:

iris