[求助]再请教OG紫色94题

94 Last year, land values in most parts of the pinelands rose almost so fast, and in some parts even faster than what they did outside the pinelands.

(A) so fast, and in some parts even faster than what they did

(B) so fast, and in some parts even faster than, those

(C) as fast, and in some parts even faster than, those

(D) as fast as, and in some parts even faster than, those

(E) as fast as, and in some parts even faster than what they did

答案是D，但我想问的是，为什么than后面要有一个逗号，怎么读都不顺呢？如果去掉逗号可不可以呢？请指点！

and in some parts even faster than 是对as fast as的一个补充，插入部分，要用逗号，你把这and……than去掉直接读也能读通。

不过我奇怪为什么后面没有个与rose 对应的 did？