Which of the following is an example of behavioral variation?
A. Parrots eat seeds, fruit, and nuts, while hawks eat meat.
B. Parrots have four claws per foot, while emus have three.
C. Parrots have bright, colorful feathers, while ostriches do not.
D. Parrots have thick, curved beaks, while hummingbirds have thin, pointed beaks.