This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'All are examples of glycosaminoglycans, EXCEPT: \nSelect and explain. \nA. Hyaluronic acid, B. Chondroitin sulfate, C. Heparin, D. None of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Glycosaminoglycans (mucopolysaccharides) are complex carbohydrates containing amino sugars and uronic acids. They may be attached to a protein molecule to form a proteoglycan. Proteoglycans provide the ground or packing substance of connective tissue. They hold large quantities of water and occupy space, thus cushioning or lubricating other structures, because of the large number of --OH groups and negative charges on the molecule which, by repulsion, keep the carbohydrate chains apa. Examples are hyaluronic acid, chondroitin sulfate, and heparin Ref: Harper 28th edition, chapter 14.', 'role': 'assistant'}]