Answer: Increased predation, and mild winters.
Explanation: As the prey population increases, there is more food for predators. So, as the number of predators increases, more prey are captured.
Mild winters would cause all of the plants to die, therefore prey would also die due to lack of food and cause predators to die as well for the same reason.
Side note: It might also be ample rainfall but I didn't know if they meant ample rainfall as in flooding or not, if it means flooding then that could be an answer, too. And I also wasn't sure if this was multiple choice or not.
Good luck! :)
