In parakeets, two autosomal genes (located on different chromosomes) control the production of feather pigments. Gene B controls the production of blue pigment, and gene Y controls the production of yellow pigment. Known recessive mutations in each gene result in the loss of pigment synthesis. Two green parakeets are mated and produce green, blue, yellow, and albino progeny.

A. Based on this information, explain the pattern of inheritance. Be sure to include the genotypes of the green parents and all four phenotypic classes, as well as the fraction of the total progeny that each phenotypic class represents in your answer.

B. The parental (green) parakeets are the progeny of a cross between two true-breeding strains. What two types of crosses between true-breeding strains could have produced the green parents? Indicate the genotypes and phenotypes for each strain?