How has the amendment process make the constitution a flexible and enduring document?

The amendment process allows the Constitution to be amended through the passing of time. There are two ways to amend the Constitution either the proposal for amendment must be approved by 2/3 of the House of Reps. and Senate or 2/3 of states can approve it at a National Constitutional Convention. Once approved, it is then ratified by 3/4 of the state legislatures or 3/4 of state held conventions. 

Your answer would be a , i hope you do very well

The first one is russia because in russia they were on the rough times and they never had a way to get out of