Answer:
D. Codominance
Step-by-step explanation:
Codominance refers to the condition when two alleles of the same gene do not exhibit any dominant-recessive pattern of inheritance. When present together, both the alleles are expressed and impart their respective phenotypes to the individuals.
The A and B alleles of ABO blood type are codominant. They both are expressed in the genotype "I^A I^B" and the individuals with this genotype have "AB" blood type. The "AB" blood type has features of both A and B alleles.