Which of the following is NOT a characteristic of complete proteins?

The correct answer highlights that complete proteins are not exclusively found in animal products. Complete proteins are those that contain all nine essential amino acids that the body cannot produce on its own. While it is true that many animal-based foods, such as meat, dairy, and eggs, are sources of complete proteins, there are also plant-based sources that can provide all essential amino acids when paired correctly. Foods like quinoa and soy products, for instance, are considered complete proteins as well.

Thus, the statement that complete proteins are only found in animal products is inaccurate, thereby supporting the selection of this option as the answer. Understanding the nature of protein sources is crucial, especially for individuals following vegetarian or vegan diets, as they can still obtain complete proteins by combining different plant foods.