The answer is c) peptidoglycan.
Peptidoglycan is a unique polysaccharide that comprises a backbone made of repeating units of two modified monosaccharides: N-acetylglucosamine (GlcNAc) and N-acetylmuramic acid (MurNAc). This structure is fundamental for the integrity of bacterial cell walls, providing strength and shape. In contrast, cellulose, starch, and glycogen are composed of unmodified glucose units, so they do not contain any modified monosaccharides.