The Treaty of Guadalupe Hidalgo, which ended the Mexican-American War in 1848, had a significant impact on the United States by increasing the debate over slavery. The treaty resulted in the U.S. acquiring a vast amount of territory, including present-day California, Arizona, New Mexico, Nevada, Utah, and parts of Colorado and Wyoming. This expansion brought the issue of whether slavery would be permitted in these new territories to the forefront of national politics, intensifying sectional tensions between the North and South.
So the correct answer is:
It increased the debate over slavery.