TOEFL Reading: ETS-TOEFL阅读机经 - 5ZAP3KA11UJ37RV1L$

In paragraph 6, the discussion of the cactus-eating moth and the prickly pear in Australia illustrates which of the following about biological control? A. Nonnative pests cannot be controlled through biological means once they have begun to spread rapidly. B. A nonnative pest can sometimes be controlled by the introduction of a nonnative predator. C. A nonindigenous pest can be controlled only by a predator that comes from the same original habitat as the pest. D. A native pest can be controlled by either a native or a nonnative predator.