The phenotype represents the physical appearance or expression of an organism's alleles. Hence the correct option is a.
The phenotype represents the observable physical characteristics or traits of an organism, which are determined by the expression of its alleles. In the context of the given chart, the phenotypes are the different fur colors—black or brown—associated with specific genotypes (BB, Bb, bb). The phenotype is influenced by the interaction of alleles at a particular gene locus.
While the genotype refers to the genetic makeup or combination of alleles an organism possesses, the phenotype is the outward manifestation of those genetic instructions. In this case, the phenotypes of black and brown fur are directly linked to the genetic information encoded by the alleles at the corresponding gene locus for fur color. Phenotypes encompass a wide range of observable traits, reflecting the complex interplay between an organism's genes and its environment. Hence the correct option is a.