All Keystone Species are Predators.Is This Accurate

Question

All keystone species are predators.Is this accurate?
A) Yes, a keystone species by definition is a predator.
B) Yes, a keystone species cannot be found at a low trophic level.
C) No, only grazers are keystone species.
D) No, any species can theoretically be a keystone species.

Accepted Answer

Any species can theoretically be a keystone species, not just predators. A keystone species is defined by its significant impact on the ecosystem, not by its trophic level or specific behavior.