Final answer:
The genotype of the calf will be Nn.
Step-by-step explanation:
In this case, since Betsy has a black nose (N) and does not carry the recessive allele for a red nose (n), she must have the genotype NN. Rudolph, on the other hand, has a red nose (n) which is a recessive trait, so his genotype must be nn. When Rudolph and Betsy have a calf, their genotypes will be Nn, as the calf will receive one dominant allele from Betsy (N) and one recessive allele from Rudolph (n).