Which plant-based source can provide complete protein when consumed in sufficient amounts?

• A. Beans
• B. Rice
• C. Soybean products
• D. Corn

Answer: (C)

Complete protein means providing all nine essential amino acids in amounts sufficient for body needs. Most plant foods lack one or more of these amino acids, making them incomplete proteins. Soybean products are among the few plant sources that offer a full, balanced amino acid profile similar to animal proteins, so when eaten in sufficient amounts they can supply complete protein. That’s why soybean products like tofu, tempeh, and edamame are the best plant-based option for achieving complete protein. Beans, rice, and corn are typically limited in one or more essential amino acids on their own, so they don’t provide a complete protein unless paired with other foods that compensate for the gaps.