The best source of protein, with the highest quality of protein is
A. Legumes
B. Nuts
C. Eggs
D. Meat

Meat is the best source for proteins.

Proteins are one of the macronutrients that are required by humans. Proteins are formed of amino acids which are digested in the Gastrointestinal tract and absorbed as simple amino acids. They are needed to be consumed as the essential amino acids cannot be produced in the body.

Now plants are also good sources of proteins. But they are high sources of one or two particular type of amino acids. The balanced amount of amino acids aren't available form them.

But animal proteins are balanced all aspects. So animal proteins are high source and best source of proteins.