What is the probability that the offspring of a homozygous dominant parent and a heterozygous parent will show a recessive phenotype?

The probability that the offspring of a homozygous dominant parent (AA) and a heterozygous parent (Aa) will show a recessive phenotype is 0%. Since the homozygous dominant parent contributes only dominant alleles (A), all offspring will inherit at least one dominant allele (A) from the homozygous parent, resulting in either a homozygous dominant (AA) or a heterozygous (Aa) genotype, both of which express the dominant phenotype.