If someone has a dominant phenotype, their genotype can either be heterozygous or homozygous. The diagram shows a Punnett square for a particular trait among two parents, but one letter of a parent’s genotype is missing.

Which describes the letter that belongs where the question mark is?

T because there are offspring that are heterozygous
T because there are offspring that are homozygous
t because there are offspring that are homozygous.
t because there are offspring that are heterozygous