Answer:
Multiple alleles is the situation where a gene (genotype) has three or more alleles, not just two.
Step-by-step explanation:
Multiple alleles or polyalelia is the situation where a gene (genotype) has three or more alleles, not just two, for the same chromosomal locus (gene address), determining a trait (phenotype). The explanation for polyallelic coexistence derives from mutagenic processes producing selected allelic series adapted to the environment.
In the human organism, the ABO system represents a typical case of multiple alleles, where dominantly and recessively, the alleles: IA, IB and i, define the four possible blood types: O, A, B, and AB.