In a particular guinea pig species, individuals may have either black or orange fur. The colors are determined by a dominant and a recessive allele at a single locus. A black male is mated to a black female.

a. If a pup with orange fur is produced, which color is dominant? Explain.

b. For the same cross between two black guinea pigs, what is the probability that the second pup and the third pup will each be black? Show your work