IT referes to WHAT?

[bhumrah]

what does IT refer to in choice E? Can some one please explain? :(


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 becoming

(E) are so lacking in math skills that it will be difficult to absorb them into a city economy becoming

[RonPurewal]

The usage of 'it' in this problem is analogous to the following: It is often difficult for people to act as mediators in their own disputes.

I'm not sure what the formal name is for this usage, but it's common enough to merit your attention.