According to the "bottom-up" theory of how ecosystems are structured, the availability of edible plants is what primarily determines an ecosystem' s characteristics since it determines how many herbivores the ecosystem can support, which in turn determines how many predators it can support. This theory also holds that a reduction in the number of predators will have little impact on the rest of the ecosystem. Which one of the following, if true, would provide evidence against the bottom-up theory? ['In an effort to build up the population of a rare species of monkey on Vahique Island, monkeys were bred in zoos and released into the wild. However, the effort failed because the trees on which the monkeys fed were also nearly extinct.', "After many of the trees on Jaevix Island were cleared, the island's leaf-cutter ants, which require a forested ecosystem, experienced a substantial decrease in population, as did the island's anteaters.", 'Plants that are a dietary staple of wild pigs on Sedif Island have flourished over the last three decades, and the population of the pigs has not changed much in spite of extensive hunting.', 'After hunting virtually eliminated predators on Rigu Island, the population of many herbivore species increased more than tenfold, causing the density of plants to be dramatically reduced.']