pp test1 第4题的解释有误?

4. Perhaps the most significant postwar trend was the decentralization of cities throughout the United States, _________ when massive highway-building programs permitted greater suburban growth.

A. and accelerated a phenomenon

B. a phenomenon that accelerated

C. accelerating a phenomenon which,

D. the acceleration of which phenomenon

答案：B

分析：考的是同位语结构，a phenomenon是 the decentralization of cities throughout the United States 的同位语。A中and为conj.，后面应该连接一个完整的句子，但缺主语，错；C中语序混乱，错； D中of which作为介词宾语，后面应该接一个完整句，但只有一个phenomenon主语，句子不完整，错。

我刚看完高分语法,说 名词+of+which+谓语动词,所以of which 后面怎么能够跟完整句呢,而且主语应该是the acceleration,不可能是phenomenon.

不知道我分析的对否?请大家讨论讨论~~~

agree with u.

D is totally wrong, I have no idea how to correct it.