The green plant cell wall is composed mainly of cellulose (linear homopolysaccharide of D-glucose units), which makes option A incorrect.
Gram positive cells are characterized by presence of single thick layer of cell wall, which is made up of peptidogycan, teichoic acid and lipoteichoic acid. Peptidoglycan is a repeating framework of long glycan chains having alternate N-acetyl glucosamine and N-acetyl muramic acid, these glycan chains are cross-linked by short peptides. This makes option B correct.
Chitin (linear homopolysaccharide of N-acetyl-beta-D-glucosamine units) is common constituent of cell walls of all type of fungi, option C is incorrect.
Viral coat is composed of rigid protein shell, which makes option D incorrect.