Which allele is an example of a dominant allele in humans?

• A. Recessive blue-eye allele
• B. A recessive allele for albinism
• C. Huntington's disease allele (H)
• D. The allele for cystic fibrosis

Answer: (C)

Dominant alleles can determine a trait even if only one copy is present. The Huntington's disease allele is a classic autosomal dominant example: having one copy (Hh) is enough for the disease to develop, though often later in life. In contrast, the other listed conditions are described as recessive, meaning two copies are typically needed to show the phenotype (blue-eye, albinism, and cystic fibrosis). So the Huntington's disease allele best fits as a dominant allele.