A 65-year-old patient complains of occasional swelling, pain, and a scraping sensation in the knees. X-rays show a narrowing of the joint space. The patient only wants to take “natural” oral products to help reverse this condition. The products available for consumption are examples of which one of the following types of compounds? (A) Proteoglycan (B) Polyol (C) Glycolipid (D) Disaccharide (E) Glycoprotein