4. 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
答案如何是C呢？as 应该接句子阿，怎么能接一个词组呢? | 
