The Amish in Pennsylvania are good examples of Cultural pluralism.
Roman law can be seen today in our governmental structure, down to the very architecture that makes up most federal buildings.
The main way in which Clause 39 of the Magna Carta was influential to the American Revolution was that it places limits on the power of the king, especially with regard to the King's ability to arrest people--meaning that the Founding Fathers drew on this as inspiration to show that they too had power.
The last one should be the correct one
Accessibility to resources, its hunger for power, the competition between it and others, and great trade relations.