How was the question of slave labor in america primarily seen in the 1850s?

As an economic question, is the right answer.

Explanation:

In the United States, slavery was the authorized system of human property servitude, essentially of Africans and African Americans, that survived in the 19th century America. Since colonial times, slavery existed in the Americas and was legal until the independence of all the thirteen colonies of America in the year 1776.

b)

it created free trade throughout the colonial territories.