question: On cold days, snakes usually lie very still and eat little or nothing, while birds usually move around and eat a lot of food. Which statement best explains this?
choices.text: Both animals are cold-blooded, but without feathers to keep warm, snakes get too cold to move. Unlike birds, snakes are warm-blooded; they must hibernate during cold weather. Unlike snakes, birds are cold-blooded; they are less affected by the cold than snakes. Unlike snakes, birds are warm-blooded; they must eat food to maintain a constant temperature.
choices.label: A B C D