Which event is necessary for an amendment to be ratified?

For an amendment to be ratified, the process outlined in the Constitution requires a two-thirds vote in both houses of Congress. This step is crucial because it ensures that any proposed amendment has substantial support from the federal legislative body, reflecting a significant consensus for change.

After passing through a two-thirds majority, the proposed amendment must then be ratified by three-fourths of the state legislatures or by conventions in three-fourths of the states. This dual requirement of congressional approval and state ratification establishes a robust framework for altering the Constitution, ensuring that amendments are not made lightly or without widespread agreement.

The other options do not align with the constitutional process for ratification. A simple majority would be insufficient as it does not demonstrate the necessary broad support required for constitutional amendments. A national referendum is not a prescribed method in the Constitution, and a vote by state governors does not hold any legal weight in the amendment process. Thus, the requirement for a two-thirds vote in both houses stands as the correct and necessary step for the ratification of an amendment.