All of the Following Are True Statements About Bacterial S-Layers

Multiple Choice

All of the following are true statements about bacterial S-layers EXCEPT:

A) They are commonly found in Gram-positive cells as well as in archaea.
B) They are a crystalline layer consisting of protein or glycoprotein.
C) They present a formidable physical barrier to predators or parasites.
D) They are found in bacteria freshly isolated from natural sources.
E) They are found in bacteria isolated from laboratory cultures.