Final answer:
The difference in eye color is the result of different pigments in the iris.
Step-by-step explanation:
The difference in eye color between Deb, who has blue eyes, and Erv, who has brown eyes, is the result of different pigments in the iris. The iris is the colored part of the eye and it controls the size of the pupil, which is the opening that allows light to enter the eye. The iris contains pigments that determine the color of the eyes.