The correct answers are B) introducing legislation into Congress and C) calling for an amendment convention.
The two procedures for ratifying and amending the US Constitution are introducing legislation into Congress and calling for an amendment convention.
The ways to ratify and amend the Constitution are the following. When the House of Representatives and the Senate propose an amendment with a two-thirds vote and the three-fourths of the state legislature. Or two-thirds of the state legislatures call on Congress to have a Constitutional Convention, and then, three-fourths of the state legislatures approve it. And two-thirds of the state legislatures call on Congress to have a Constitutional Convention, and three-fourths of the states approve it.