How did the reintroduction of wolves to Yellowstone national park affect the beaver population?

the wolves increased the population by eating a competitor
the wolves decreased the population by eating beavers
the wolves decreased the population by eating beavers prey
the wolves increased the population by eating beavers predators

The reintroduction of wolves to Yellowstone National Park had a positive effect on the beaver population by decreasing their predators. Before the reintroduction of wolves, the elk population had increased significantly and had started to overgraze the vegetation, which is also an important food source for beavers. The presence of wolves helped keep the elk population in check, allowing the vegetation to recover and providing more food for beavers. As a result, the beaver population thrived with the reintroduction of wolves. Therefore, the statement that best describes the impact of wolves on the beaver population is: the wolves increased the population by eating beavers' predators.