If we have these two, then we produce a black coat color. If we have this and this, then we produce a black coat color. So we see that different types of possibilities create different types of coat colors. Now, in this particular case, so we see that if we have either a homozygous dominant or a heterozygous for the Z gene, we're always going to produce a dark coat color, either black or chocolate. And these depends on the second type of gene. But if we have a homozygous recessive for the D gene so if both of these alleles on this homologous chromosome pair are lowercase DS, if they're recessive, then it doesn't matter what the second type of gene phenotype is, we're always going to produce a light coat color.