which increased sectional tensions in the 1850s?\nthe mexican - american war\nthe mexican cession\nthe…

Brief Explanations:

The Fugitive Slave Act (part of the Compromise of 1850) required that escaped slaves be returned to their owners, even if found in free states. This angered many in the North who opposed slavery, as it forced them to participate in the slave - holding system. It was a major source of sectional tension between the North and the South in the 1850s. The Mexican - American War (1846 - 1848) and the Mexican Cession (1848) happened before the 1850s. The California Gold Rush (1848 - 1855) was more about economic migration and development rather than directly causing the kind of sectional tension related to the core slavery issue like the Fugitive Slave Act.

Answer:

the Fugitive Slave Act