Concept:Proteins are large molecules made up of smaller building blocks called amino acids.Explanation:Protein molecules are polymers formed by linking many amino acids together. Each protein is composed of one or more long chains of amino acids. These amino acids are organic compounds that combine in specific sequences to give a protein its unique structure and function. The body needs 20 different amino acids to grow and function properly. Of these, nine are essential and must come from food. The other options are incorrect: Glucose is a carbohydrate unit, fatty acids are units of lipids, and vitamins are micronutrients, not the primary building blocks of proteins.Answer:B. Amino acid