What is required for a constitutional amendment to be ratified?

For a constitutional amendment to be ratified, it requires the approval by three-fourths of the states. This means that after an amendment is proposed, it must be accepted by 38 out of the 50 states in order to become part of the Constitution. This process is designed to ensure that amendments to the Constitution reflect a broad consensus among the states, maintaining a balance between federal and state powers.

Other options do not align with the established constitutional process. A simple majority in both houses of Congress is necessary for proposing an amendment, but this does not pertain to ratification. A national referendum is not a required step in the constitutional amendment process and is not used in the United States. Similarly, ratification does not solely require a two-thirds majority in the Senate; a broader consensus among the states is what ultimately validates an amendment.