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 M is for having Thomsen disease, and the allele m is for not having Thomsen disease.
Ellen, a human from this group, has Thomsen disease. Ellen has two alleles for having Thomsen disease.
Based on this information, what is Ellen's genotype for the Thomsen disease gene?
A. having Thomsen disease
B. MM
From the given choices, choose the correct answer and respond with the letter of that choice.

B