The statement that best explains why the addition of a bill of rights was necessary to ensure ratification of the Constitution is:
The Anti-Federalists were fearful of a too powerful national government.
The Anti-Federalists argued that the proposed Constitution did not adequately protect individual liberties and feared that a strong national government would infringe upon the rights of the people. The addition of a Bill of Rights was a crucial compromise that addressed these concerns and helped secure the Constitution's ratification.