At Midcentury, Which of the Following Had a Major Impact

At midcentury, which of the following had a major impact on life in the United States?

A) The nation had grown far less powerful overall, which caused opposing groups to turn their attention to domestic issues such as slavery.
B) Abolitionists were becoming far less militant, so pro-slavery southerners had a harder time taking them and their intentions seriously.
C) The Compromise of 1850 still appeared to be a powerful, long-term solution to the issue of slavery, and the sudden onset of the Civil War came as a total shock.
D) Constant political conflict over slavery had led a growing number of people to decide the United States could no longer be a nation "half free and half slave."
E) Issues such as the fate of slavery in the Kansas Territory helped bring people with opposing views together and offered a concrete example of effective policy.