参考答案：B

解析： The company, which was not the sole source of the pollution but is the only business working on the cleanup, has already spent several million dollars installing ventilation systems and creating a network of wells, pumps and filters to extract chemical contaminants from groundwater. The vapor problem came to light in 2003 as a result of air-quality tests sought by residents.事实细节的找寻和判断。根据文章语义因果关系可推断地下水中的污染物蒸发造成空气污染，这一点与题干说法相符，但就地下水的来源，通过原文“The company，which was not the sole source of the pollution”可推测，被污染的地下水并非只来自该公司一家，因此，该题的说法是错误的。 注意：对关键词的正确理解有助于解题，如原文相关处一词“sole”意为“唯一的”，可帮助听者推测既然该公司不是唯一的污染源，那么被污染的地下水就不会只来自该公司一家。