The correct answer is c) codominance. In codominance, both alleles in a heterozygous individual are fully expressed, resulting in a phenotype that showcases traits from both homozygous parents. This means that when an individual inherits different alleles from each parent, neither allele is dominant or recessive. Instead, the traits blend together without overshadowing one another.
For example, in human blood types, individuals with type AB blood inherit one allele for A and one for B. Both traits are visible in the phenotype, demonstrating the principles of codominance. This contrasts with incomplete dominance, where the resulting trait is a blend of the two alleles, leading to a third phenotype that is distinct from both parent traits.