Final answer:
Human eye color is the trait best described as multifactorial because it is influenced by multiple genes, making it a polygenic trait with a wide variety of possible phenotypes.
Step-by-step explanation:
The trait that is best described as multifactorial is human eye color. Multifactorial traits are polygenic, meaning they are controlled by more than one gene and often by many genes, with each contributing to the phenotype in a small way. This contrasts with single-gene traits, where the phenotype is determined primarily by the alleles of one gene. Human eye color involves the interaction of multiple genes, and this interaction can lead to a wide range of possible phenotypes.
Human blood type and seed shape in peas are examples of traits that are commonly controlled by a single gene, making them clear examples of Mendelian inheritance. In contrast, traits such as eye color, which exhibit a wide range of variation and can be influenced by multiple genes as well as environmental factors, are considered polygenic. This complexity is evident in the many possible shades of human eye color, illustrating the concept of multifactorial inheritance.