One item that native Americans wouldn't trade was land since they believed that the land belonged to everybody and the concept of private property was anathema to them. They would trade the fruits of the land like the animal furs but not the land itself.
Im pretty sure its eaither b or c hope it helps
The main way in which the Marshall Plan impacted the European economy in the post-World War II era was by providing billions of dollars of aid to make sure that Europe didn't fall into the kinds of conditions that lead to tyrannical leaders.
