Which statement correctly describes the structural role of peptidoglycan in gram-positive bacteria?

• A. Peptidoglycan is only found in the inner membrane of gram-positive bacteria.
• B. Peptidoglycan is absent in gram-positive bacteria.
• C. Peptidoglycan forms a thin layer surrounded by an outer membrane.
• D. Peptidoglycan forms a thick layer that is the main component of the cell wall.

Answer: (D)