How can amendments be added to the U.S. Constitution?

The process for adding amendments to the U.S. Constitution is established in Article V, which allows for two primary methods: formal and informal measures.

Formal amendments can be proposed either by a two-thirds majority in both the House of Representatives and the Senate or by a convention called for by two-thirds of the state legislatures. Once proposed, an amendment must be ratified by three-fourths of the state legislatures or by conventions in three-fourths of the states.

Informal amendments occur through judicial interpretation, legislative actions, executive actions, or societal changes, which can also alter how the Constitution is applied without changing the text itself.

The other options do not align with the constitutional process; a presidential veto does not play a role in the amendment process, there's no automatic amendment after a timeframe, and unanimous consent of the states is not a requirement for amendment ratification. Therefore, the ability to add amendments through either formal or informal means by Congress and the states accurately reflects the constitutional procedures involved.