Context: This passage describes the Thomsen disease trait in humans:

In a group of humans, some individuals have Thomsen disease and others do not. In this group, the gene for the Thomsen disease trait has two alleles. The allele for not having Thomsen disease (m) is recessive to the allele for having Thomsen disease (M).
Madelyn is a human from this group. Madelyn has the homozygous genotype MM for the Thomsen disease gene.
Based on this information, what is Madelyn's phenotype for the Thomsen disease trait?
A. not having Thomsen disease
B. having Thomsen disease
From the given choices, pick the correct answer and respond by indicating the letter of the correct option.

B