Which were outcomes/effects of the Civil War?

The Civil War confirmed the single political entity of the United States, led to freedom for more than four million enslaved Americans, established a more powerful and centralized federal government, and laid the foundation for America's emergence as a world power in the 20th century.

Explanation:

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

necessary and proper clause. the congress shall have power to all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this constitution in the government of the united states, or in any department or officer thereof.