The passage implies which of the following about beavers? A. Bank beavers are unable to successfully compete with dam beavers when resources become scarce. B. Differences in dam-building behavior among beavers do not necessarily imply multiple beaver species. C. Building dams eventually causes beavers to deplete nearby resources. D. When conditions permit, beavers are more likely to build dams than burrows or lodges. E. In beavers, dam-building is an acquired rather than an innate skill.