During protein digestion, proteins are broken down into smaller molecules called peptides and then into individual amino acids. Amino acids are the basic building blocks of proteins. In cells, the process of protein synthesis constructs needed proteins by linking together these amino acids. Many cellular processes depend on the digestion and synthesis of proteins.

diagram showing digestion of protein into amino acids, and synthesis of amino acids into protein

There are 21 amino acids that make up all the proteins in every living organisms. Protein can be found in a variety of foods. Although animal products tend to have more proteins, certain nuts and grains are also good sources of protein.

Based on this information, which example best shows how proteins can be rearranged through chemical reactions to form new molecules?
A.
Proteins in the muscle tissue of animals can be broken down into amino acids and then remade into other needed proteins, but proteins found in plants cannot be broken down.
B.
Amino acids from nuts and grains change into different amino acids in an animal's digestive system, and then they rearrange to form needed proteins like those that make up skin.
C.
Proteins from plants can be taken in by an animal and broken down into amino acids, which can combine in new ways to form the muscle tissue the animal needs to grow.
D.
Amino acids in animals can be connected to form the proteins needed to repair the skin, but amino acids stay separated in plants and do not form proteins.