An ecologist studied the same species of deer during the summer and the winter. She noticed that during the summer, when there was plenty of food, the deer were energetic and playful. However, during winter when food was scarce, the deer moved more slowly and did not run unless they needed to escape a predator. Which scientific fact is best supported by her observations?
A.
Some deer species will eat the bark of trees.
B.
Food is the fuel that gives animals energy.
C.
Food provides building materials that animals use to grow.
D.
Carnivores eat primarily the meat of other animals.