The Kansas-Nebraska Act of 1854 was a significant development in the ongoing debate over slavery in the United States. The correct answer is option 1 - The Missouri Compromise was repealed and people of Kansas and Nebraska were allowed to determine whether they should own slaves or not.

Before the act, the Missouri Compromise of 1820 had established a boundary, known as the Mason-Dixon Line, dividing the country into territories where slavery was allowed and where it was prohibited. However, the Kansas-Nebraska Act repealed this compromise, allowing the residents of the territories of Kansas and Nebraska to decide for themselves whether to allow slavery.

Option 2 suggests that the act did not permit the territories the right to vote over the question of slavery, which is incorrect. In fact, the act specifically allowed the residents to vote on the issue.

Option 3 suggests that the act muzzled the voice of the majority regarding slavery, which is not mentioned in the question or directly related to the Kansas-Nebraska Act.

Option 4 suggests that the federal government had sole authority to decide on slavery, which is incorrect based on the provisions of the Kansas-Nebraska Act.

In summary, the Kansas-Nebraska Act of 1854 repealed the Missouri Compromise and allowed