Most of Portugal

[RUICHENGQ622]

Most of Portugal’s 250,000 university students boycotted classes in a one-day strike to protest a law that requires them to contribute $330 a year toward the cost of higher education, previously paying $7 per year.
A.year toward the cost of higher education, previously paying $7 per year
B.year toward the cost of higher education, for which was previously paid $7 per year
C.year, compared to the previously $7 per year, toward the cost of higher education
D.year toward the cost of higher education, instead of the $7 per year required previously
E.year as opposed to the $7 per year required previously for the cost of higher education
The OA is D, but I can't figure out why A,B,C,E are wrong?? the meaning of the sentence is that because students are required to pay 300 because of a law, but they previously paid 7, so they boycotted to protest the law.
In choice A, "previously paying $7 per year"correctly modifies the students ,I don't see why its wrong
In choice B, why the invered sentence is not correct, it acceptable i think
In choice C, and E I think both are ok
need some help!!

[RonPurewal]

please search the forum before you post. thank you.
https://www.manhattanprep.com/gmat/foru ... t1100.html

also, that thread is locked because the problem is not from an allowed source. we can't host any further discussion of this problem on the forum.