It is best to think of the amendment process as a decision tree. At a few points along the way, there are decisions that have to be made by several actors in order to move to the next phase in the sequence. Explained broadly, amending the Constitution is a two-stage process. In the first stage, amendments are proposed by one of two methods: they can be proposed by a two-thirds vote in both the House and the Senate or by a national convention called by Congress in response to petitions by two-thirds of the states. Of these two methods of proposal, only the first has ever been employed.
If either of those two decisions is made, then an amendment moves to the ratification phase of the process. Ratification can also be done using one of two methods: a proposed amendment has been ratified when it has been approved by the legislatures of three-fourths of the states or by special ratification conventions held in three-fourths of the states. Of these two methods of ratification, the second has only been used once—to ratify the 21st Amendment, which repealed Prohibition.
Why does the text describe the amendment process as a decision tree? Choose the BEST answer.