1. In rats, a black-tailed mutant was discovered. When it was crossed to a pink long-tailed rat, 4 offspring were black-tailed and 3 were pink tailed. Two of these black-tailed rats were crossed and they produce 6 black tailed and 3 pink-tailed rats. These experiments were repeated several times with approximately the same results. Never was a case seen where a mating between two black-tailed rats produced all black-tailed rats. Explain the black X pink tail and black X black crosses in terms of the alleles of the gene involved in tail length and the genotypes of the rats in the crosses and their offspring.