Which of the following statements about inulin, cellulose, chitin, and dextran are true?

• A. I, II
• B. I, III
• C. I, II, III
• D. I, II, IV

Answer: (D)

The key idea here is that the four substances are all polysaccharides, but they differ in their building blocks and how those blocks are linked, which determines their structure and properties. Inulin is a fructan, built from fructose units. Cellulose is a polymer of glucose joined by beta-1,4 glycosidic bonds, forming straight, rigid chains. Chitin is similar in backbone to cellulose but uses N-acetylglucosamine as its repeating unit, also connected by beta-1,4 bonds. Dextran, on the other hand, is a glucose polymer that uses alpha glycosidic linkages (mainly alpha-1,6) with branching.

These distinctions explain why the correct option includes statements that accurately describe monomer identity and linkage types for each polymer, and why a statement claiming a uniform monomer or a uniform type of linkage for all four would be false. So the choice that reflects those true structural features—recognizing the fructose nature of inulin, the glucose backbone of cellulose, the N-acetylglucosamine unit in chitin, and the alpha-linked glucose skeleton with branching in dextran—best fits the facts.