Final answer:
The correct term for characteristics encoded by genes at multiple loci is polygenic characteristics, which include traits like skin color, height, and eye color. These traits can have a wide range of phenotypes and are determined by the interaction of multiple genes, making their inheritance complex.
Step-by-step explanation:
The characteristics encoded by genes at many loci are termed polygenic characteristics. Polygenic characteristics are controlled by more than one gene, and each gene may have multiple alleles. The inheritance of these traits is quite complex due to the involvement of multiple genes potentially on nonhomologous chromosomes, and as a result, these characteristics can display a wide range of possible phenotypes.
Examples of polygenic characteristics include skin color, adult height, and eye color. For instance, eye color is determined by the interaction of at least eight genes, each with their own alleles, highlighting the complexity of these traits. Additionally, traits such as height and weight are also considered polygenic because they can be measured and show a great deal of variation within a population.
The observable traits expressed by an organism, such as those resulting from polygenic characteristics, are referred to as its phenotype. In conclusion, the correct answer to the question is a) polygenic characteristics.