Which possible step in the amendment process has never been used?

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2 points
Amendments can be proposed with support of two thirds of both the House and the Senate
Amendments can be proposed by a national convention called by two thirds of the state legislatures
Amendments can be ratified with approval of three fourths of the state legislatures
Amendments can be ratified with approved by special conventions in three fourths of the states

Amendments can be proposed by a national convention called by two thirds of the state legislatures