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

谢谢！

B解释不通吧.proposed projects at a cost***.翻译成以***的成本提出了project.

还是要在句子意思的基础上做题.

谢谢啊

明白了一些，有时候做题就会太关注于语法结构而有些忽略意思了