GMAT Sentence Correction (SC) | Re: In the U.S. Presidential election of 1876

In the U.S. Presidential election of 1876, Democrat Samuel Tilden clearly won the popular vote, but after party leaders resolved disputes about electoral votes in four states, they declared Republican Rutherford B. Hayes the winner, Tilden's supporters acquiescing in exchange for the withdrawal of Federal troops from the South.

A) Tilden's supporters acquiescing in exchange for the withdrawal of Federal troops
B)with Tilden's supporters acquiescing because, in an exchange, Federal troops withdrew
C)