Italy is the correct answer
During the 1850s, tensions between the North and South increased as the nation decided to how to incorporate the vast territories that had been acquired during the Mexican-American War of 1846-1848. The question of whether each territory was to be slave or non-slave worsened sectional tensions.
The Wilmot Proviso aimed to ban slavery in territory acquired from Mexico after the Mexican American War.
Those that were supportive of the Proviso were American citizens who were 1. opposed to the institution of slavery and 2. wanted to force the issue of slavery as a national issue. #2 is especially important as during this period, many were hoping to ignore the national issue of slavery or at least keep it from becoming the dominant national issue.
