How did the land gained in the mexican cession affect political party unity in the united states a. debate over immigration b. it broke party unity over the issue of slavery c. it strengthened party unity in the whig party d. it did not significantly affect party unity

b.it broke party unity over the issue of slavery

The land gained in the Mexico cession brought about slavery which became the centre of debate among official from the United States and Mexico. This also caused the separation of political parties in the United States. To end slavery, during President Lincoln’s period in office, the American war started and this caused the gap between the Northern and Southern states intensified.