What can we learn about trade in North America from copper bells?

a. It's impossible that the copper bells given to Cabeza de Vaca came from Santa Rita.

b. The copper mine was established to replace gold as the standard form of currency.

C. No one had a use for soft copper when it was first mined, so it was not traded for European goods.

d. Trade in copper has existed for about 1,000 years.

c. No one had a use for soft copper when it was first mined, so it was not traded for European goods.