Question 18 is based on the passage you have just heard.

听力原文

        Pigs are not native to North America. They were first introduced to California by Spanish and Russian explorers and settlers many centuries ago. (16) [In the early times, pigs were allowed to wander freely in search of food. This practice also allowed many pigs to escape from farms and live in the wild, which became a problem.] In fact, they’re one of the most damaging invasive species on the continent. Wild pigs cause millions of dollars in crop damage yearly. (17) [They also harbor dozens of diseases that threaten both humans and farm animals.] Forest patches with wild pigs have been found to have considerably reduced plant and animal diversity. In addition to either eating other animals or their food supply, wild pigs damaged native habitats by rooting up grasses and rubbing on trees. Their activities may also create opportunities for invasive plants to colonize these areas. Wild pigs will eat almost anything containing calories. Mice, deer, birds, snakes and frogs are among their victims. They can also harm other wild species through indirect competition rather than eating them or shrinking their food supply. On one particular United States island, wild pigs themselves became an attractive food source for a species of mainland eagle. (18) [The eagles began breeding on the island and also feeding on a species of native fox. The foxes were almost wiped out completely.]

18. What does the passage say about the native foxes on a US island?（关于美国某个小岛当地的狐狸，这篇文章说了些什么？）

解析：C。录音结尾提到，老鹰在这座岛上繁殖，并猎食一种当地的狐狸，这些狐狸因此几乎遭到灭顶之灾。C项是对这一内容的概括总结，故为正确答案。

错项排除：A项在录音中无依据，故排除。录音中说该小岛当地的狐狸几乎遭到了灭顶之灾，而不是它们的食物都吃光了，故B项错误；D项与此内容相悖，故错误。