Which of the following is an example an a national state dispute that could not be solved by the constitution?

(a) fighting in the Mexican war (b) secession of states during the civil war (c) the addition of the Louisiana territory (d) passing that no child left behind Act

I choose (b) secession of states during the civil war. It was unconstitutional to secede from the Union. When Lincoln was elected President of the United States, many in the South feared that it would mark the end of slavery which many of the plantation class relied on. Rather than let that happen, they seceded from the Union and this led to Civil War.