Context: In a group of budgerigar parakeets, some individuals have green body feathers and others have blue body feathers. In this group, the gene for the body feather color trait has two alleles. The allele B is for green body feathers, and the allele b is for blue body feathers.
Koko, a budgerigar parakeet from this group, has blue body feathers. Koko has two alleles for blue body feathers.
Based on this information, what is Koko's phenotype for the body feather color trait?
A. bb
B. blue body feathers
Identify the correct choice from the options below and respond with the letter of the correct option.

B