Which two constitutional provisions have been at the heart of constitutional struggles between federal and state powers throughout american history?

The correct answer is: the elastic clause and the Tenth Amendment

According to the elastic clause, Congress has the power to make laws. The sole legislative power is vested on Congress. According to the Tenth Amendment, the powers of the federal government are those vested by the Constitution

Tenth amendment and the elastic clause

Explanation:

The Tenth Amendment to the United States Constitution, presented by James Madison, restrains the intensity of the government.

By including this change, it made it extremely evident that any power not conceded to the government was saved for the state governments.

Elastic clause is a proviso in the U.S. Constitution that engages the Congress to establish laws that are essential and appropriate for completing its forces. This clause is authoritatively known as the Necessary and Proper proviso.  

the answer is a. laws were enacted in the aftermath of the plot to make it harder to free slaves,increasing sectionalism