Carbohydrates

Step 1: Understanding the Concept: Cellulose is a complex carbohydrate (polysaccharide) that forms the primary structural component of plant cell walls.
Step 2: Key Formula or Approach: Identify the monomeric repeating unit of the polymer cellulose to determine its composition.
Step 3: Detailed Explanation: Cellulose is a homopolymer, meaning it is made up of only one type of monosaccharide repeating unit.
These repeating monomeric units are exclusively -D-glucose molecules.
They are linked together by -1,4-glycosidic bonds to form a long, straight, and unbranched chain.
Therefore, cellulose is entirely made up of glucose units.
Step 4: Final Answer: The correct option is (3).