Final answer:
Ben Franklin was influenced by the Iroquois Confederacy's written constitution, leading to the idea of a written constitution (B) for the United States.
Step-by-step explanation:
Ben Franklin, along with other Founding Fathers, admired the political system of the Iroquois Confederacy, which influenced the democratic principles incorporated into the United States Constitution. The concept that they took inspiration from would be (B) The idea of a written constitution.
The Iroquois League had a constitution known as the Great Law of Peace which governed the way their confederacy operated, similarly, the framers of the United States Constitution created a written document that outlined the laws and principles of the government. While they also embraced Enlightenment ideas and lessons from previous republics, the ethos of written governance from the Iroquois played a role in shaping their thoughts on constitution-making.