labrador retrievers (breed of dog) have a gene [b] encoding an enzyme that makes hair pigment. the allele for black coat color (b) is dominant to the allele for brown coat color (b). however, there are multiple genes that determine the dog's coat color. if a lab has two copies of the recessive allele for a pigment-depositing gene (ee), it can only have a yellow coat color, regardless of whether the dog carries either a b or b allele for gene b. in a cross of two doubly heterozygous black labs (bbee x bbee), what fraction of the next generation would one expect to be yellow?