Final answer:
To initiate a national convention for amending the U.S. Constitution is 10 states. The correct answer is option 1) 10 states.
Step-by-step explanation:
According to Article V of the US Constitution, a national convention to amend the Constitution can be called by Congress if two-thirds of both houses agree or if two-thirds of the legislatures of the states request it.
In this case, it would require the legislatures of at least ten states to request a national convention to amend the Constitution. The correct answer is option 1) 10 states.