What type of protein provides all essential amino acids in sufficient quantities?

The correct answer is complete protein, which refers to protein sources that contain all nine essential amino acids in adequate amounts necessary for human health. Essential amino acids are those that the body cannot synthesize on its own and must be obtained through diet. Sources of complete proteins are typically derived from animal products such as meat, eggs, and dairy, though some plant-based sources, such as quinoa and soy, also fall into this category.

In contrast, incomplete proteins lack one or more of the essential amino acids, which is typical of most plant proteins like beans, nuts, and grains. A protein blend usually refers to a combination of different protein sources, which may or may not provide all essential amino acids depending on the specific ingredients included. Animal protein specifically refers to proteins sourced from animals, which are generally complete, but the term is broader and does not exclusively define the concept of complete proteins. Therefore, while animal protein can be a source of complete protein, "complete protein" specifically identifies the quality of the protein itself in terms of its amino acid content.