Why Is the African Elephant Considered a Keystone Species

Why is the African elephant considered a keystone species?

A) Elephants eat more food than any other species in their community.
B) Elephants live in large cooperative herds that dominate other smaller groups within the community.
C) The removal of elephants from their community would result in drastic changes in the ecological structure of the community.
D) Elephant populations are larger than the populations of any other organisms in their community.
E) It is the largest organism in its community.