Answer:
4. Monomers
Explanation:
Monomers are small and simpler substances that are bonded together to form large and complex polymers. Many amino acids are bonded by a peptide linkage to form complex polypeptides. Here, amino acids are the monomers while the polypeptides are the polymers. Glucose molecules are bonded by a glycosidic linkage to form cellulose or starch or glycogen. Here, glucose is a monomer while cellulose, starch, and glycogen are the polymers. Therefore, macromolecules are made up of monomers.