Context: This passage describes the Marfan syndrome trait in humans:

In a group of humans, some individuals have Marfan syndrome and others do not. In this group, the gene for the Marfan syndrome trait has two alleles. The allele for not having Marfan syndrome (m) is recessive to the allele for having Marfan syndrome (M).
Kevin is a human from this group. Kevin has the homozygous genotype mm for the Marfan syndrome gene.
Based on this information, what is Kevin's phenotype for the Marfan syndrome trait?
A. having Marfan syndrome
B. not having Marfan syndrome
Answer with the option's letter from the given choices directly.

B