Non-Alaskan grizzly bears are indicator species for mountain ecosystems. In the nineteenth century, the grizzly bear nearly went extinct in the lower forty-eight states and were eventually added to the federal Endangered Species List as a threatened species in 1975. Ranching and farming have driven the grizzly from the open plains. and today the species lives mostly in mountains and forests. The reason for including the grizzly in the list of animal indicator species is that
A) they are easily counted in the projected range area for this species.
B) they have long been considered a threatened species in their natural habitat.
C) they are a key indicator of habitat fragmentation and the dwindling supply of food resources in the animal's range.
D) the decline of the grizzly bear population or the health of those remaining signal air and water pollution in the range area.