Coat color in mice is determined by two independently assorting but interacting genes. The dominant allele at the Black locus (B) results in a black pigment being deposited in the fur; the recessive allele (b) leads to no pigment being made and an albino phenotype. The dominant allele (A) at the other locus, Agouti, results in a wild type or agouti’ pigment pattern; the recessive allele (a) results in only the black pigment being seen. The bb phenotype is epistatic to the A- phenotype. In a testcross of Aa Bb mice X aa bb mice, what fraction of the progeny would have albino fur?