The correct answer is A) bb
Step-by-step explanation:
In genetics, an allele is a variation of a gene, which often determines a physical trait. Alleles are classified as dominant if they express even when there are other alleles or as recessive if two copies of the same allele are needed for the gene to express. Moreover, in genetics dominant alleles are represented by uppercase letters while recessive alleles are represented by lowercase letters.
In this context, the allele that is responsible for the brown coat in rabbits is a recessive allele, considering this is represented by lowercase b. This means two copies of the allele are necessary for the rabbit to have a brown coat and therefore the genotype of a brown coat is bb. Also, others such as Bb and BB have the dominant allele related to the black coat, and therefore will lead to rabbits with a black coat.