When two different alleles of a gene are both fully expressed in a heterozygote, but neither allele is dominant over the other, it is called

a. Incomplete dominance

b. codominance

c. dihybrid dominance

b. codominance

Explanation:

Usually, alleles of a gene show dominant-recessive relationship where one allele is completely dominant over the other one and if they are present in heterozygous condition, the dominant allele will be expressed.

However codominance is a phenomena where both the alleles are fully and equally expressed. So when the the two alleles are present together, neither is able to dominate and they both will show their own trait. The result is that both type of traits are present in the organism.