Final answer:
Of the Whig, Free-Soil, and Know-Nothing parties, C. 'each dissolved in the 1850s' is the most accurate, as their structured influence largely ended in that decade. The Whigs disintegrated over slavery, and the Know-Nothings and Free-Soil Parties merged with others or declined due to internal divisions.
Step-by-step explanation:
The Whig, Free-Soil, and Know-Nothing parties each occupied a unique place in the political landscape of the United States during the antebellum period but shared certain characteristics. Looking at the options provided, C. 'each dissolved in the 1850s' would be the most accurate statement. While not all of these parties dissolved precisely in the 1850s, their influence or existence as structured entities primarily ended in that decade. The Whigs disintegrated due to internal divisions over slavery after the election of 1852. The Know-Nothing Party, which rose in the 1850s, was centered on nativist issues but foundered on slavery's divisive role, leading to its decline. The Free-Soil Party, established to prevent the expansion of slavery into new territories and states, eventually merged with others to form the Republican Party. None of these parties existed in a recognizable form by the 1860s, and only the Free-Soil Party had some success by impacting the political dialogue around slavery and joining with other anti-slavery elements to create the Republican Party.