role of keystone

By feeding on the dominant species in a community, keystone predators serve to sustain species variety by ensuring that the dominant predators do not completely wipe out the various species. Therefore, the correct answer is (b) prey on the community's dominant species.

A keystone species is an organism that helps define an entire ecosystem. Without its keystone species, the ecosystem would be dramatically different or cease to exist altogether. Keystone species have low functional redundancy.