In the context of variations of dominance, which statement best defines a dominant allele?

• A. An allele that produces an intermediate phenotype only when paired with a different allele.
• B. An allele that is expressed only when two identical copies are present in a homozygote.
• C. An allele whose phenotype is expressed in a heterozygote, masking the effect of the other allele at the same locus.
• D. An allele that is always the most common in a population regardless of its phenotypic effect.

Answer: (C)