With more than 17000 islands, ________ only 6000 are inhabited, Indonesia is the world's largest archipelago(岛国)．
A.on whichB.for whichC.of whichD.along which在线课程C
解析：
“超过17000个岛屿，其中只有6000个有人居住，印尼是世界上最大的岛国。介词加which构成的定于从句，相当于only 6000 of the 17000 islands are inhabited，用of which 来表示。