What activity in new spain enabled spain to become the richest nation in europe and probably the world? question 8 options: dominating the canadian fur trade extracting silver from the land using slave labor conquered thousands of spanish settlements capturing and herding buffalo to send back to europe?

The correct answer is

extracting silver from the land using slave labor

They would do this using slaves from both the local population and the slaves from Africa. The fur trade and the buffaloes were mostly taken care of by France. Conquering thousands of settlements never happened but they did conquer quite a few.