The genotype that will have brown fur is bb. The genotype that will have brown fur is bb because the letter "b" represents the allele for brown fur, while the letter "B" represents the allele for black fur. Since brown fur is the desired trait, the genotype must have two copies of the brown fur allele, which is represented by "bb". If an organism has one copy of the brown fur allele and one copy of the black fur allele (Bb), then it will have black fur, since the black fur allele is dominant over the brown fur allele.