The best answer is "A". It was a deal between Republicans and Southern Democrats that led to the presidency of Rutherford B. Hayes.
In February 1877, at a meeting held in Washington's Wormley Hotel, the Democrats agreed to accept a Hayes victory and to respect the civil and political rights of African Americans on the condition that Republicans withdraw all Federal troops from the South, thus consolidating Democratic control in the region.
On March 2, the congressional commission voted along party lines to award all the disputed electoral votes to Hayes, giving him 185 votes to Tilden's 184.