A. to acquaint the reader with water pollution problems B. to alert the reader to the dwindling water supply C. to explain industrial uses of water D. to demonstrate various measures to solve the pollution problem 参考答案:A 答案解析:第一段第一句是本文的主题句,指出污染问题的严重性,接着作者阐明了主题句所点出的主旨。第一段最后一句是本段的结论句,指出必须立即采取严厉的措施来解决水的污染问题。所以,正确答案非[A]莫属。