According to the law of dominance the recessive genes are always masked by the dominant genes. In this case, the genes for brown fur will mask those for white fur. Thus, a cross between homozygous will yield brown fur rabbits in the F1 generation (heterozygous). If the F1 are selfed according to the Punnet square we get a mixture of brown fur bunnies and white fur bunnies in the ratio of 3:1. Hence, if there are 160 bunnies then 120 of them have brown fur and 40 have white fur.
Therefore, the correct answer is 40 bunnies.
