Final answer:
The correct answer is (C). To make a high-quality protein, two lower-quality complementary proteins must be consumed within the same day, not necessarily at the same meal or at the exact time.
Step-by-step explanation:
Complementary proteins are a combination of two or more incomplete protein sources that together provide all the essential amino acids your body needs. These protein sources do not necessarily have to be consumed at the same time to be effective. According to current nutritional guidance, complementary proteins should be consumed within the same day to meet the essential amino acid requirements.
For example, if a grain (which might be low in one essential amino acid) is eaten at breakfast, and a legume (which has the amino acid that the grain lacks) is consumed at dinner, this combination throughout the day would provide a balanced amino acid profile similar to that of a high-quality protein.