Which of the following best explains why the number of organisms at each level decreases while moving up the energy pyramid? A. The animals at each level use energy, so only a small amount of their energy is available to the next level. B. The animals at each level have more predators, so they produce more offspring. C. The animals at higher levels are more competitive, so fewer animals survive. D. The animals at higher levels move more than animals at lower levels, so they require more energy.