Read the selection from the section "Gettysburg (July 1-3, 1863)." Although Antietam was a setback to Lee's plans, the Union failed to take advantage of the situation. Lincoln replaced McClellan, but his new generals lost decisively at Fredericksburg, Virginia (December 13, 1862), and Chancellorsville, Virginia (April 30 – May 4, 1863). Which two words would BEST replace "setback" and "decisively" in the selection above? (A) (B) (C) (D) obstacle; mysteriously impediment; clearly catalyst; courageously revitalization; horribly