Answer: Codominance
Explanation: We have dominant genes and recessive genes.
Dominant gene are gene that are been expressed. example for a tall individual (TT) it means the gene for tallness is been expressed while a recessive gene are genes that are not been expressed .Example An individual who is short (tt) could have the gene for tallest in a recessive form but expresses shortnes.
Complete dominance occur when both allele present are expressed in the phenotype of an individual i.e non of the gene expression is masked or recessive. Codominance is a deviation from mendelian's principle of Inheritance and often time result into a new phenotype.
E.g A white plant cross with a Red plant should give a Red colored plant in an heterozygous form in the first filial generation but when there is codominance i.e both allele are expressed we have a pink plant instead of Red
RR×rr =RrRr