Question

cellulose is made of special non - digestible monomers but glycogen and starch are made of different monomers
cellulose contains covalent bonds but not glycogen or starch.
the arrangement of the monomers in cellulose make it impossible to be broken down without special enzymes.
glycogen and starch are water soluble and can be dissolved to begin digestion.

Explanation:

Cellulose is a structural polysaccharide in plants. Its monomers are arranged in a way that makes it resistant to digestion by most organisms without specific enzymes. Glycogen and starch are storage polysaccharides, and their structures allow them to be more easily broken - down for energy. Glycogen and starch are water - soluble to some extent for digestion processes, but this is not the main difference in digestibility compared to cellulose. All three (cellulose, glycogen, starch) are made of glucose monomers and all contain covalent bonds.

Answer:

The arrangement of the monomers in cellulose make it impossible to be broken down without special enzymes.