According to Janda, et al$.,$ an amendment to the Constitution can be proposed by a

two$-$thirds vote in both the House of Representatives and the Senate or by

Constitutional conventions in three$-$fourths of the states.

national convention, called by Congress at the request of one$-$third of state legislatures.

Constitutional conventions in one$-$third of the states.

national convention, called by Congress at the request of two$-$thirds of state legislatures.

national convention, called by Congress at the request of three$-$fourths of state legislatures.