请问2题，谢谢

GWD7-Q15:

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

为啥答案是D而不选B呢？

Unlike the original National Museum of Science and Technology in Italy, where the models are encased in glass or operated only by staff members, the Virtual Leonardo Project, an online version of the museum, encourages visitors to “touch” each exhibit, which thereby activates the animated functions of the piece.

1. exhibit, which thereby activates

2. exhibit, in turn an activation of

3. exhibit, and it will activate

4. exhibit and thereby activate

5. exhibit which, as a result, activates

答案是D，是不是activate少了个s啊？

第一题，whose cost的whose指代projects，只听说过at the cost of doing，意思是以。。为代价，没听说过at the cost doing

第二题，activate是和touch并列的，是由visitors发出的动作

visitors touch....and activate

touch这个动作激发动画功能