请教为啥B错！？

frankzhiwei

The city has proposed a number of water treatment and conservation projects the cost of which raises water bills high enough so that even environmentalists are beginning to raise alarms.



A.the cost of which raises water bills high enough so that

B.at a cost raising water bills so high that

C.at a cost which raises water bills high enough so

D.whose cost will raise water bills so high that

E.whose cost will raise water bills high enough so that

答案是D，我选了B，请问能分析一下吗？
谢谢~

luopite

个人觉得可能是B中raising的修饰对象有歧义，但是只是可能……换了我自己来做的话很油可能也选B了。
at a cost raising water bills so high that 这里raising可以做cost的定语来修饰cost，同样也可以修饰句子的主语raising。
拙见求大牛解答

frankzhiwei

怎么whose都用上了这里，哎~

海谷007

我觉得at  a cost 修饰了动词proposed 所以不恰当，D的话就很清楚是修饰名词projects的

bispham

记得prep也出现过用whose修饰物的，gmat似乎不太在意whose和of which的区分；
今天刚做到这套题,也一度在B和D中纠结，感觉如楼上的NN们说的，现在分词有跳过at a cost修饰The city has proposed ... projects的歧义