This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'The bacterial cell wall has all of the following properties except: \nSelect and explain. \nA. It consists of a mixed polymer called peptidoglycon, B. It is the structure principally responsible for the reaction of gram staining, C. It is a unique flexible plastic structure, D. It contains D-isomers of amino acids', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]