阅读下列短文, 从给的四个选项 (A、B、C和D) 中, 选出最佳选项。
(2013·西安市标准化考练，D)
Up to 45 rare species of Australian animals are in danger of becoming extinct within 20 years, scientists warned in a report. But hope is not lost! According to the report, the species can be saved if immediate action is taken to control their natural predators (天敌) and other threats.
