Which of the following is an example of adaptation?
a) a rabbit population in which all of the members change fur color from brown to white as the seasons change.
b) a butterfly population where each individual makes more of an enzyme for processing plant toxins as its exposure to toxic plants increases.
c) an eagle population where adult eagles develop a tolerance for invasive mites over five years.
d) a fish population in which the average skin brightness decreases over several generations in the presence of predators.