Which political party expended the most effort to portray itself as the group that was most committed to defending the plain folk of the antebellum South?

The whigs and democrats

Explanation:

The Whig Party was formed in 1834 as a political party by rivals of President Andrew Jackson and his fellow Jacksonian Democrats group which was led by Henry Clay, the name “Whigs” was coined out from the English antimonarchist party and was an effort to depict Jackson as "King Andrew."

Whigs general political view was in defending the plain folk of the antebellum South, support of higher tariffs, distributing land incomes to states and passing legislative bills on relief and bailouts in response to the financial panics of 1837 and 1839.

did mary wollstonecraft believe was a natural ingredient for women’s happiness?

so you should go with

a. strong