A. The Columbian Exchange was a series of interchanges that permanently changed the world's ecosystems and changed nearly every culture around the world.

B. Native Americans taught the Europeans local farming methods and introduced them to new crops and foods, such as corn, tobacco, and the potato. Europeans also adapted many devices invented by the Indians, such as the canoe.

C. The Europeans introduced the Native Americans to many crops, such as wheat, oats, and barley and to domestic livestock. The Europeans introduced the Native Americans to technologies, such as metalworking. Europeans also brought diseases that killed millions of Native Americans because they lacked immunity to the diseases.