The answer is; B
If we assume that the allele for black fur is B and that for white fur is b, crossing a homozygous black rabbit with a heterozygous black rabbit, will yield the following results (indicated in the punnet square below);
Genotypically, 50% of the population will be homozygous dominant, while 50% will be heterozygous. However, phenotypically, all offspring will bear black fur because the black fur allele is dominant over the grey allele.
