Final answer:
The Kansas-Nebraska Act of 1854 allowed residents of the Kansas territory to decide for themselves whether to allow slavery through popular sovereignty, leading to the conflict known as Bleeding Kansas.
Step-by-step explanation:
The question concerns the provision that was included in the Kansas-Nebraska Act of 1854 regarding the residents of the Kansas territory and slavery. The correct answer is that residents of the Kansas territory were allowed to decide for themselves whether to allow slavery, as the bill applied the principle of popular sovereignty to the territories. This was a contentious decision as it effectively repealed the Missouri Compromise line and opened new territories to the possibility of slavery, depending on the outcome of local elections. This led to significant conflict in the region known as Bleeding Kansas, as pro- and antislavery forces clashed over the outcome of these elections.