Which best illustrates a result of natural selection?

Natural selection is best illustrated by the phenomenon where certain traits become more common in a population because they provide some advantage for survival and reproduction. A classic example of this is the adaptation of the peppered moth (Biston betularia) during the Industrial Revolution in Britain.

Before the Industrial Revolution, peppered moths were predominantly light-colored, which helped them to camouflage against the light-colored trees and lichen, thus protecting them from predators. However, as industrial pollution killed the lichens and darkened the trees with soot, the darker-colored moths, which were initially rare, had a camouflage advantage and became less visible to predators. As a consequence, the frequency of the dark-colored form increased over time because they survived at higher rates and produced more offspring. This is a result of natural selection, where the environment favored the survival of one color variant over the other, leading to a change in the population's genetic makeup over successive generations.