Which crops from the Americas significantly changed diets in the Old World?

• A. Rice and millet.
• B. Maize and potatoes.
• C. Oats and rye.
• D. Wheat and barley.

Answer: (B)

After 1492, crops brought from the Americas transformed Old World diets by providing new, reliable sources of calories that could be grown in a variety of environments. Maize and potatoes stood out because they are highly productive and adaptable. Maize, or corn, thrives in diverse climates and soils and yields a lot of calories per acre, making it easy to feed large populations and to use as both human food and animal feed. Potatoes offer even more efficiency: they deliver a lot of energy in a small area, tolerate poor soils and cool growing conditions, store well, and can be grown in regions where other staples struggle. Together, these crops dramatically boosted food security and supported population growth where earlier staples limited expansion.

The other options—rice and millet; oats and rye; wheat and barley—are staples that were already established in the Old World and originated there, so they did not introduce new crops from the Americas. Maize and potatoes were the recent introductions that most significantly expanded and diversified diets in Europe, Africa, and parts of Asia.