A) A trophic cascade occurs when populations of predators and prey are disturbed by some abiotic event. B) A trophic cascade occurs when a primary succession unfolds. C) A trophic cascade is a process whereby abundances of a predator are reduced, and as a result, the prey's own resources increase in abundance. D) A trophic cascade is a process whereby predators reduce abundances of their prey, and as a result, abundances of the prey's own resources increase.