Which of the following correctly identifies key elements present on the exterior of Gram-negative (GN)and Gram-positive (GP)bacteria?

A)GN: single lipid bilayer;GP: two lipid bilayers
B)GN: single peptidoglycan layer;GP: multiple peptidoglycan layers
C)GN: extensively crosslinked peptidoglycans;GP: uncrosslinked peptidoglycan
D)GN: contains both N-acetylmuramic acid and N-acetylglucosamine;GP: contains only N-acetylmuramic acid
E)none of the above