For rock pocket mice, fur color is a phenotype
Phenotypes refer to the morphological characters of organisms.
In other words, phenotypes refer to the physical appearance of living organisms.
In this case, the appearance of the rock pocket mice varied from darker fur on the black rock to lighter-colored fur on the lighter-colored rock. This means that the phenotype varies with the environment.
More on phenotypes can be found here: https://brainly.com/question/20730322