Context: In a group of rats, some individuals have a normal-sized body and others have a dwarf body. In this group, the gene for the body size trait has two alleles. The allele B is for a normal-sized body, and the allele b is for a dwarf body.
Stuart, a rat from this group, has a normal-sized body. Stuart has two alleles for a normal-sized body.
Based on this information, what is Stuart's genotype for the body size gene?
A. BB
B. a normal-sized body
Select the correct answer from the provided options and reply with the letter associated with it.

A