请教OG-11th-118 也是白勇unit8 40

flywer

103. Students in the metropolitan school district lack math skills to such a large degree as to make it difficult to absorb them into a city economy becoming ever more dependent on information-based industries.
(A) lack math skills to such a large degree as to make it difficult to absorb them into a city economy becoming
(B) lack math skills to a large enough degree that they will be difficult to absorb into a city’s economy that becomes
(C) lack of math skills is so large as to be difficult to absorb them into a city’s economy that becomes
(D) are lacking so much in math skills as to be difficult to absorb into a city’s economy becomin
(E) are so lacking in math skills that it will be difficult to absorb them into a city economy becoming

白勇上的解释我看不懂啊   麻烦大家帮我讲一下这题为什么选E吧
白勇上说

这些累赘啊什么的要怎么解释啊   我觉得我完全分不出来啊
搜了讨论帖发现这题是OG11里面的118题   但是我买的是12版的书  如果有原版的解释的话  可以麻烦发给我看下么  
谢谢大家啦