In some forests and parks that contain varieties of flowering trees and shrubs, there are signs that read "Take nothing but pictures; leave nothing but footprints. These signs help people remember that -- A. all animals feed directly on flowering shrubs that may be removed by people.

B. humans can disrupt habitats by removing flowering trees and shrubs

C. the removal of flowering trees and shrubs will increase biodiversity

D. flowering shrubs grow best in state forests and parks