Context: This passage describes the shell banding trait in Cepaea snails:

In a group of Cepaea snails, some individuals have a banded shell and others have an unbanded shell. In this group, the gene for the shell banding trait has two alleles. The allele for a banded shell (B) is dominant over the allele for an unbanded shell (b).
A certain Cepaea snail from this group has the homozygous genotype bb for the shell banding gene.
Based on this information, what is this snail's phenotype for the shell banding trait?
A. a banded shell
B. an unbanded shell
Answer with the option's letter from the given choices directly.

B