What are proteins primarily made of?

Proteins are primarily made of long chains of amino acids. These amino acids are the building blocks of proteins and are linked together through peptide bonds to form polypeptide chains. The sequence and arrangement of these amino acids determine the protein's structure and function. Each protein has a specific sequence of amino acids that dictates how it folds into its three-dimensional shape and how it interacts with other molecules within the cell. This fundamental aspect of protein structure is why option B accurately describes the composition of proteins.

While nucleotides make up nucleic acids like DNA and RNA, fatty acids are components of lipids, and sugars typically form carbohydrates, it is the amino acids that are crucial for the formation of proteins, underscoring the importance of option B in this context.