An individual has type ab blood. The father has type a and the mother has type b. What is the individual's phenotype an example of

Codominance

Explanation:

Codominance is a type of inheritance pattern in which two alleles of a gene both express themselves in a heterozygous state. Codominance occurs when neither of the two alleles involved are recessive instead both dominate simultaneously.

As described in this question, the father of an individual has type A blood and the mother has type B. However, the individual has type AB blood. This is because alleles for blood types A and B both phenotypically express themselves in the individual. Hence, blood type A and B are said to be codominant and the AB phenotype is showing an example of CODOMINANCE.