Context: This passage describes the scale type trait in common carp:

In a group of common carp, some individuals have normal scales and others have mirror scales. In this group, the gene for the scale type trait has two alleles. The allele A is for normal scales, and the allele a is for mirror scales.
A certain common carp from this group has normal scales. This carp has one allele for normal scales and one allele for mirror scales.
Based on this information, what is this common carp's genotype for the scale type gene?
A. normal scales
B. Aa
Identify the correct option from the choices provided and respond with the letter of the correct option.
Answer: B