Based on this information, what is Moxie's phenotype for the coat pattern trait?

 - solid coloring
 - white spots
Moxie's genotype for the coat pattern gene is aa. Moxie's genotype of aa has only a alleles. The a allele is for white spots. So, Moxie's phenotype for the coat pattern trait must be white spots.
To check this answer, consider whether Moxie's alleles are dominant or recessive. The allele for solid coloring (A) is dominant over the allele for white spots (a). This means A is a dominant allele, and a is a recessive allele.
Moxie's genotype of aa has only recessive alleles. An organism with only recessive alleles for a gene will have the recessive allele's version of the trait. So, Moxie's phenotype for the coat pattern trait must be white spots.