If a homozygous dominant parent (AA) mates with a homozygous recessive parent (aa), what percentage of their F1 offspring will express the dominant phenotype?

✓ Correct Answer: Option D

All F1 offspring will be heterozygous (Aa) and express the dominant phenotype because they inherit at least one dominant allele from the homozygous dominant parent. The dominant allele will mask the recessive allele.