What requirement must be met for an amendment to be ratified?

To ratify an amendment to the U.S. Constitution, it is essential that the amendment receives approval from three-fourths of the state legislatures or by conventions in three-fourths of the states. This requirement ensures that any change to the Constitution reflects a broad consensus among the states, which is critical for maintaining the foundational principles of federalism and representative government.

The process is designed to be deliberately challenging, emphasizing the need for significant agreement across diverse political and geographic lines. This safeguard helps prevent hasty or impulsive changes to the Constitution, ensuring that amendments reflect the will of a substantial majority of the states. The inclusion of this requirement highlights the framers' intention to create a stable yet adaptable governing document that serves the needs of all states.

The other options, while relevant to the legislative process, do not pertain to the specific requirements for constitutional amendment ratification. For instance, a majority vote in Congress is necessary to propose an amendment but does not apply to its ratification. Presidential approval is not required for constitutional amendments. Similarly, a national referendum is not part of the constitutional amendment process, as the Constitution does not stipulate this method.