Which of the following was a primary outcome of the Civil War?

The preservation of the Union was a primary outcome of the Civil War, which lasted from 1861 to 1865. The conflict arose mainly due to deep-seated issues such as states' rights and slavery. When the Southern states seceded from the Union, there was a significant threat to the very fabric of the nation. The war was fought to bring these states back into the fold and maintain the integrity of the United States.

Ultimately, the war concluded with the defeat of the Confederate states, leading to their reintegration into the Union. This outcome solidified the federal government's authority over the states, ensuring that the nation remained united as one sovereign entity. The preservation of the Union was crucial not only in preventing the fragmentation of the United States but also in setting the stage for future civil rights advancements and the eventual abolition of slavery through the 13th Amendment.

The other options, while significant in their own rights, do not relate directly to the primary aims and outcomes of the Civil War. The establishment of the United Nations occurred in the aftermath of World War II, the expansion of U.S. territory happened through various means long before the Civil War, and the introduction of the 18th Amendment, which prohibited alcohol, is entirely separate from