大家好，想请教一则短篇阅读: There have been numerous well-documented extinctions of indigenous species caused by the introduction of non-indigenous predators and pathogens. However, surprisingly few extinctions of indigenous species can be attributed to competition from introduced species. For example, during the past 400 years, 4,000 plant species have been introduced into North America, and these non-indigenous plants currently account for nearl y 20 percent of North America's plant species. Yet no evidence exists that any indigenous North American plant species became extinct as a result of competition from new species could mean that such extinctions take longer to occur than scientists initially believed or, alternatively, that extinctions are rarely caused by competition from non-indigenous species. 题目是: The passage is concerned primarily with: A pointing out that a particular type of species extinction is rarely known to occur. B proposing a possible explanation for conflicting data about a particular type of species extinction. C resolving a debate about the frequency of a particular type of species extinction. D comparing two theories regarding possible causes of a particular type of species extinction. E refuting a proposed explanation for the increasingly rare occurrence of a particular type of species extinction. 主要是想问A和B两个选项，考满分答案给A，但我认为B选项也没有错，conflicting data 就是非原生种没有造成原生种灭绝的数据，所以作者在最後一句话给了一个解释，所以我 认为B选项也是对的QQ，想请教版上大大帮忙解惑，谢谢。 --

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