How Did the Mexican-American War Affect Sectional Tensions in the U.S

How did the Mexican-American War affect sectional tensions in the U.S.?

A) Tensions were appeased because of the expansion of slavery.
B) New ties between the Old and New Northwest increased national harmony.
C) Linked by railroads, the entire country entered a period of unprecedented harmony.
D) It eased North-South tensions because of the acquisition of new territory.
E) It exacerbated North-South conflicts because of the slavery issue.