Which term describes an organism's observable characteristics that result from its genotype?

The term that describes an organism's observable characteristics resulting from its genotype is phenotype. Phenotype encompasses various traits, including physical looks, behavior, and physiological functions, that can be influenced by the genetic makeup of the organism as well as environmental factors.

Genotype refers specifically to the genetic constitution of an organism—essentially the alleles that an individual possesses—and does not account for how those alleles are expressed physically. The term trait refers to a specific characteristic, which can be a part of the phenotype. Mutation refers to changes in the DNA sequence that can lead to changes in genotype and, therefore, potentially influence phenotype, but it does not specifically describe the observable characteristics themselves.

Thus, phenotype is the best term to encompass the range of observable traits that arise from the interplay of an organism's genotype and its environment.