Which genotype would represent a hybrid organism?

A hybrid organism is one that possesses two different alleles for a given trait, indicating heterozygosity. In genetic terms, a hybrid would typically be represented by a genotype that includes one dominant allele and one recessive allele. The notation "Aa" illustrates this concept perfectly, as it comprises one uppercase "A" (representing the dominant allele) and one lowercase "a" (representing the recessive allele).

In contrast, the other genotypes presented (AA and aa) represent homozygous conditions where the organism has either two dominant alleles or two recessive alleles, respectively. The genotype "ab" could imply two different alleles, but without the context of whether they are dominant or recessive, it does not fit the standard genetic classification of alleles regarding a single trait. Therefore, "Aa" distinctly represents a hybrid organism, confirming its status as a heterozygous genotype for that specific trait.