[求助]请教OG-29 的B

girdle

请教OG 29  的B, 29. The number of people diagnosed as having a certain intestinal disease has dropped significantly in a rural county this year, as compared to last year, Health officials attribute this decrease entirely to improved sanitary conditions at water-treatment plants, which made for cleaner water this year and thus reduced the incidence of the disease. Which of the following, if true, would most seriously weaken the health officials’ explanation for the lower incidence of the disease? (A) Many new water-treatment plants have been built in the last five years in the rural county. (B) Bottled spring water has not been consumed in significantly different quantities by people diagnosed as having the intestinal disease, as compared to people who did not contract the disease. (C) Because of a new diagnostic technique, many people who until this year would have been diagnosed as having the intestinal disease are now correctly diagnosed as suffering from intestinal ulcers. (D) Because of medical advances this year, far fewer people who contract the intestinal disease will develop severe cases of the disease. (E) The water in the rural county was brought up to the sanitary standards of the water in neighboring counties ten years ago. 为什么B是支持呢？B说喝水的量不是导致疾病的原因，原文说疾病减少的原因，我觉得不是一个概念，这样不能作为排除它因支持吧，请大家指点！！！

cranberry

说明没有别的原因影响,是支持.

girdle

可是原文比的是今年得病得和去年得病得人数，B比的是有病和没病的？还是不明白

cranberry

呵呵，明明说的是有病没病的都消费这个水，说明水不是得病的原因，而不在于水的量

girdle

明白了，谢谢

newmania

还是不明白~

既然水不是原因，那么那个"water-treatment plants"导致的" made for cleaner water"也就不是原因了?这样不就weaken了?

请指教~~

cranberry

大家看逻辑的时候一定不能象在看阅读文章,文章说的是水处理厂，这个选项说的是瓶装水，有关系么？

newmania

nod,,晓得了~~

多谢^_^