The main failure of the Articles of Confederation was that it gave too much power to the states, basically the states were all divided into their own governments. The national government have too little power and couldn't properly control the states. The US Constitution was created to balance out the powers between state and national government.
Most slaves lived on plantations, but the plantations were not very big: they rarely had more than 100 slaves. The best answer is then A. lived on plantations with 20 or more slaves.
Made government less centralized
