Answer:
"They believed Lincoln would take away their rights as Southerners."
Step-by-step explanation:
According to www.enotes.com, "Lincoln was very popular in the North, but the South did not think highly of him. Southerners were convinced Lincoln would completely ruin their way of life by abolishing slavery and turning their lives upside down."
Using this information, I can infer that the answer "They believed Lincoln would take away their rights as Southerners." is the correct answer, although, "They believed the issue of slavery was relatively unimportant." is a good contender.