Which of the following led to the most sectional strife over slavery in the first half of the 19th century?

Assuming that this is referring to the same list of options that was posted before with this question, the correct response would be "Manifest Destiny" since this mentality led to the expansion of the United States--therefore forcing the question of whether each new state would be free or slave.

Ithink it’s a : ) good luck on whatever