The Congress of Vienna helped ensure peace in Europe by making sure that a common consensus was reached between the leaders of a variety of countries--making it more of a multilateral and multi-beneficial agreement that suited all.
Answer:
It proclaimed the freedom of slaves in the ten Confederate states still in rebellion. It also decreed that freed slaves could be enlisted in the Union Army, thereby increasing the Union's available manpower.
So I'm guessing D or B.
The Compromise of 1877 was a purported informal, unwritten deal that settled the intensely disputed 1876 U.S. presidential election. It resulted in the United States federal government pulling the last troops out of the South, and formally ended the Reconstruction Era.
