Answer: The correct answer is C) Community stability.
Keystone species is an individual species or a group of species of plants and animals, which play a significant role in maintaining the structure of community and the functioning of ecosystem.
This means that when these species are removed from an ecosystem, they will result in the dramatic changes in the structure and functioning of the ecosystem.
Example- In terrestrial habitats, fire ants behaves like a keystone species ( a predator keystone species) that suppresses the number of individuals and species of arthropods, which could have harmful effects in the agriculture.
