The correct option is B Maize
The exchange introduced a wide range of new calorically rich staple crops to the old world namely potatoes, sweet potatoes, maize, and cassava. The primary benefit of the new world staples was that they could be grown in old world climates that were unsuitable for the cultivation of old world staples. Maize is a gift of new world to old world because as it is a major staple among the natives of the new world.