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? a. t because there are offspring that are heterozygous b. t because there are offspring that are homozygous c. t because there are offspring that are homozygous. d. t because there are offspring that are heterozygous.