Answer:
The correct answer is keystone predator.
Explanation:
In sustaining the composition of an ecological community, a keystone species plays an essential function. In the absence of keystone species, the ecosystem would fail to exist and would become drastically different. A predator is a classic illustration of a predator, which inhibits a specific herbivorous species from eradicating the dominant species of plants. In the non-existence of predators, the herbivorous prey would increase enormously and would clean the entire essential plant species, and thus, drastically change the significance of the ecosystem.