Final answer:
Peptidoglycan is a material composed of NAM and NAG and is present in bacterial cell walls, but not all prokaryotic cells. Option B is correct while D and E are incorrect because Archaea do not have peptidoglycan in their cell walls.
Step-by-step explanation:
Peptidoglycan is correctly described as B) a material composed of N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG), and it is indeed present in the cell walls of bacteria. However, it is not present in all prokaryotic cells because the cell walls of Archaea do not contain peptidoglycan. Instead, Archaeal cell walls have a distinct composition that lacks this particular polymer. This makes option D incorrect because it claims that peptidoglycan is present in all prokaryotic cells, which is not accurate. Therefore, the material in question is a complex polysaccharide, but it is not found universally in all prokaryotic cells, making option E also incorrect.