Sentence Correction

362
In a plan to stop the erosion of East Coast beaches, the Army Corps of Engineers proposed building parallel to shore a breakwater of rocks that would rise six feet above the waterline and act as a buffer, so that it absorbs the energy of crashing waves and protecting the beaches.

(A) act as a buffer, so that it absorbs
(B) act like a buffer so as to absorb
(C) act as a buffer, absorbing
(D) acting as a buffer, absorbing
(E) acting like a buffer, absorb

[spoiler]OA-C
Imo-b[/spoiler]

IMO "B" is wrong since "so as" together is never correct in GMAT.

idiom is so [adjective]....as [verb]

goelmohit2002, Could you plese elaborate on why "so as" together is NEVER correct?

IMO the answer is C, but I would like a clarification on this 'so as' rule.

as I mentioned in the above post...idiom is

so [adjective] as [verb]....

since it is breaking the idiom...so it is never correct in GMAT playground.