Question

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

Explanation:

The iris is the pigmented, circular muscle in the eye that regulates the size of the pupil. It controls the amount of light entering the eye by adjusting the pupil's diameter. The other options (Violet, Lily, Ivy, Daphne) are names of flowers and have no relation to the eye - structure described.

Answer:

iris