Final answer:
The US Constitution provided a model plan of government to other nations, creating a structured federal system and influencing the development of constitutions around the world. The correct answer is option: the US Constitution
Step-by-step explanation:
The document that provided a model plan of government to other nations is the US Constitution. After the ineffective governance under the Articles of Confederation, which had significant limitations like the inability to enforce laws or collect taxes, the US Constitution was created to address these shortcomings and provide a strong framework for government.
It established a federal system with separated powers, a balance between state and federal authorities, and a bicameral legislature, which has since influenced numerous other nations in the development of their own constitutions.