Which of the following statements describes a proximate cause?
A) Snowshoe hares turn white in winter because the fitness of their ancestors was enhanced by camouflaging themselves from predators.
B) People sleep at night because a molecule that accumulates during the day has an effect on the sleep centers of the brain.
C) Birds often show elaborate courtship displays because this behavior increases the ability of the bird to attract a mate, which leads to enhanced fitness.
D)Birds have hollow bones because hollow bones increased the fitness of their ancestors by allowing them to run faster and capture prey more efficiently.