Labrador dogs have three coat colors recognized by breeders. Black Labradors have dark black fur. Chocolate Labradors have brown fur. Yellow Labradors have very light tan fur. In Labradors, fur color is determined by two genes, Ext and TyrP1. A recessive mutation in the Ext. gene ( E x t ) prevents the production of black pigment. A single Ext + allele is sufficient for wild-type Ext activity, which produces black pigment. Yellow Labradors have the genotype Ext / / Ext and therefore do not produce black pigment. The production of black pigment can be blocked by recessive mutation in the TyrP1 gene ( T P 1 ) even in the presence of wild-type Ext alleles. Brown Labradors have at least one wild-type Ext allele and a TyrP1 / TyrP1 genotype. A single TyrP1 + allele is sufficient to allow the production of black pigment. A breeder crossed a male Labrador that is heterozygous for both genes ( E x t + / E x t ; T r P 1 + / T r P 1 ) with a female Labrador with the same genotype. The Ext and TyrP1 genes are inherited independently. (a) Identify the phenotype of the female (mother) dog in the cross. (b) Calculate the proportion of the offspring from this cross that are expected to have a TyrP1 / T P1 genotype. (c) Calculate the proportion of the offspring from this cross that are expected to be chocolate Labradors..