Who were the free-soilers?

a) wealthy southern planters

b) antislavery settlers from the northeast

c) farmers seeking land grants

The free-soilers were antislavery settlers from the northeast who opposed to the expansion of slavery to the Western United States, considered free soil, so anyone moving to these territories should be regarded as a free person.

The free-soilers were antislavery settlers from the northeast (option B). They received the name because they argued that free men on free soil was not only morally but also econimically superior than slavery. As the Free Soil party they were formed by many different anti slavery groups, such as the Barnburners.