该题有一定难度，不仅是语言问题的难度，还有理性分析的难度。各个选项 相比之下A 更符合题意，其内容在录音中有提及，且与所问的leads to chemical pollution相符。其他选项都不正确，这并不是因为其内容与录音所说矛盾，而是这些并不直接导致（ leads to ) 化学污染。

[重点难点]
理解问题关键词，抓住主要信息。

[录音原文]
More than 49 million chemicals are commercially available today, yet less than 1 percent of them are inventoried or regulated. The life cycle of these chemical compounds extends well beyond the use for which they were originally intended. Many seep into the soil，air， rivers and sea. Moreover， many of them have not historically been considered as contaminants, such as pharmaceuticals, which are present in water and the wider environment.