For many cities in the world, there is no room to spread our further, New York is an exam

For many cities in the world, there is no room to spread our further, New York is an example.
A. for which
B. in which
C. of which
D. from which

A. for whichB. in which(答案→)C. of whichD. from which解析：of which引导的间隔性非限制性定语从句， 对cities起补充、说明的作用。介词of的选择取决于和前面名词的搭配 of the cities。

谢谢了