How can the Constitution be amended?

The process for amending the Constitution is intentionally challenging to ensure that changes reflect a broad consensus across the federal and state levels. The correct answer highlights that an amendment must first achieve a two-thirds majority vote in both houses of Congress, which demonstrates significant legislative support. After passing Congress, 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-step requirement ensures that any amendment has widespread approval, thus preserving the foundational principles of both federalism and representative democracy enshrined in the Constitution.

The other methods listed, such as simple majority votes, presidential decrees, or national referendums, do not apply to the amendment process. A simple majority vote would not sufficiently ensure broad support, while presidential decrees lack the constitutional authority to alter the document. Similarly, national referendums are not a mechanism established by the Constitution for making amendments, emphasizing the unique and rigorous process outlined within the document itself.