Answer:
48
Step-by-step explanation:
In genetics, additive effects represent a mode of quantitative inheritance that occurs when the combined effects of alleles (i.e., the variants of a gene that lead to differential expression of a phenotypic trait) at two or more loci are equal to the sum of their individual effects, contributing thus to the final phenotype. Therefore, the additive variance can be explained by the sum of the individual effects of identified loci/genes that have an additive effect on this quantitative trait. In this case, each gene shows an additive effect (equal to 8 for each dominant allele), thereby the phenotypic value corresponding to the genotype AABbCcDD will be equal to 48 (i.e., 16 + 8 + 8 + 16 = 48).