Final answer:
Hardy-Weinberg equilibrium is characterized by the constancy of allele frequencies in the absence of evolutionary forces such as natural selection, and the correct answer is C. Natural selection has no effect on Hardy-Weinberg equilibrium.
Step-by-step explanation:
The concept of Hardy-Weinberg equilibrium indicates that in the absence of factors such as natural selection, mutation, genetic drift, migration, and non-random mating, the allele frequencies in a population will remain constant from generation to generation. The best characterization of Hardy-Weinberg equilibrium among the options provided is C. Natural selection has no effect on Hardy-Weinberg equilibrium. This is because the Hardy-Weinberg principle assumes a population in equilibrium without any evolutionary forces acting upon it, implying that when these forces, such as natural selection, are absent, the allele frequencies do not change. The other options provided either do not accurately describe the Hardy-Weinberg equilibrium (A, B, D) or relate to specific applications of the principle (E), but do not characterize the state of equilibrium itself.