Wheat, cattle, and horses are common sights in North America today. Why?
a. These species are indigenous to North America.
b. Native Americans in North America acquired these species through their trade with indigenous people in the South Pacific.
c. Horses and cattle migrated to North America from northern Russia on their own via an ice bridge that has since melted; the wind carried wheat seeds into the region.
d. Europeans deliberately brought them to the region during their 400 years in North America.
e. Native Americans brought them to North America when they arrived some 12,000 years ago.