You are interested in two traits in rabbits, each of which is controlled by a separate gene with two alleles:

a) coat color (brown, b, is completely dominant to white,

b) and tail (tailed, t, is completely dominant to tail-less,

c) you cross a brown, tailed rabbit that is heterozygous at both loci with a white, tail-less rabbit and produce a large number of offspring.

among the offspring you find only two phenotypes in equal proportions: brown, tailed and white, tail-less.