Final answer:
Union victories in the South, especially the fall of Atlanta, played a crucial role in Abraham Lincoln's reelection in 1864.
Step-by-step explanation:
Union victories in the South helped Lincoln win reelection in 1864. The fall of Atlanta in September and General Philip Sheridan's successes in the Shenandoah Valley were pivotal Union victories that bolstered Lincoln's popularity and greatly contributed to his reelection bid. In the face of a peace movement and the anti-war sentiments of the Copperhead Democrats, these military successes reassured many of the Union's eventual victory, leading to Lincoln's overwhelming support, even among Union army troops. The support from the Union army troops also contributed to Lincoln's victory.
Answer: A. Union victories in the South