The answer is B) Atlanta.
Why is it B)? because the Battle of Atlanta in the summer of 1864 was a complete victory for the Union forces commanded by William Tecumseh Sherman. When the city of Atlanta fell to Sherman's forces, the Union gained control of the Georgia Railroad Line, which in turn gave them control of almost all of the railroads in the "Deep South." With control of the railroads came control of Confederate supply lines and shipping.