Final answer:
The fur color in Labrador retrievers is an example of codominance, where both alleles are expressed and contribute to the phenotype.
Step-by-step explanation:
The fur color in Labrador retrievers is an example of codominance. The fur color is controlled by two alleles, E and B. Dogs with the ee genotype develop yellow fur, B_E dogs have black fur, and bbE dogs have chocolate fur.
In codominance, both alleles are expressed and contribute to the phenotype, resulting in both black and yellow pigments being produced in the fur of Labrador retrievers.