Final answer:
Tofu, which is made from soy, is the only option listed that is a complete protein because it contains all nine essential amino acids required for a healthy diet.
Step-by-step explanation:
Among the options provided, D) Tofu is a complete protein. Complete proteins are those that provide adequate amounts of all nine essential amino acids, which our bodies cannot synthesize and must obtain from our diet.
While most plant foods tend to offer incomplete proteins, meaning they lack one or more essential amino acids, soy products, including tofu, are an exception to this rule and contain all the essential amino acids, making them complete proteins. It's important for those with plant-based diets, such as vegetarians and vegans, to include such complete protein sources or to combine different plant foods, like rice and beans, to ensure they receive all necessary amino acids.