Rudolph the Reindeer has a red nose (n), which is a recessive trait. Betsy the Reindeer has a black nose (N), which is a dominant trait, and she does not carry the recessive allele. Assume the rules of human genetics also apply to reindeer. A. Either NN or Nn
B. Nn
C. NN
D. nn

black, black, black, red

Explanation:

If there is a dominant allele present, any recessive alleles are ignored and the reindeer displays the trait associated with the dominant allele.

Therefore A, B, and C have black noses because they have 1 or more dominant alleles

D has two recessive alleles so it displays the recessive trait.

Hope this helps.

B. Nn

Explanation:

We know Betsy does not have recessive allele which means she is a homozygous dominant, NN. Rudolph has a red nose which is recessive trait, to get a recessive trait you need to be homozyogus recessive, nn.

Now, if you cross NN x nn (assuming you know how to do punnet squares), all the offsprings will be Nn (black nosed)

Hope its right!