locus. The allele for brown eye color is dominant to the allele for brick red eye color and to the allele for white eyes. C) There is more than one gene for eye color. The brown mutation and the white mutation occur in separate genes and are both recessive to the wild type alleles.  The offspring are heterozygous for both genes, so they are phenotypically wild type. D) None of the above. It is not possible for a cross between a white-eyed and a brown-eyed fly to produce wild type offspring.

a) 1/3 b)1/2 c)1/8

In Drosophila, the allele for long legs (sl*) is wild-type and the allele for short legs (sl) is mutant. The allele for gray body color (b*) is wild-type and the allele for black body color (b') is mutant. The loci for leg length and body color are linked. Flies with sl*sl* b*b* genotypes are mated with flies that have sl s bb genotypes. A testcross was then performed in which the F, offspring with sl*sl b*b genotypes were mated with flies with sl sl. b'b genotypes. The phenotypes of 1000 offspring were recorded. There were 470 flies with long legs and grey body, 30 flies with long legs and black body, 30 flies with short legs and grey body, and 470 flies with short legs and black body. Which of these phenotypes are parental phenotypes? VWhich of these phenotypes are recombinant phenotypes? What is the distance between these two gene loci in centiMorgans (map units)?

The answer is "D" but can you explain in a short summary why D is the answer please