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.

1. the cost of which raises water bills high enough so that
2. at a cost raising water bills so high that
3. at a cost which raises water bills high enough so
4. whose cost will raise water bills so high that
5. whose cost will raise water bills high enough so that

答案是不是B啊

其他的读起来好别扭啊

仔细看看D，倒也说得过去。。

confused。。。。

我查到了。whose是代词的所有格，它既可以代人也可以代物。当代物的时候，它相当于of which.

Please show me the book whose cover is red. == Please show me the book the cover of which is red.