Context: In a group of pea plants, some individuals have a tall stem and others have a short stem. In this group, the gene for the stem height trait has two alleles. The allele for a short stem (h) is recessive to the allele for a tall stem (H).
A certain pea plant from this group has the heterozygous genotype Hh for the stem height gene.
Based on this information, what is this plant's phenotype for the stem height trait?
A. a tall stem
B. a short stem
Select the correct answer from the provided options and reply with the letter associated with it.

A