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': 'Which one of the following  bacteria is  cell  wall  deficient? \nSelect and explain. \nA. Escherichia  coli, B. Salmonella  typhi, C. Mycoplasma, D. Treponema pallidum', 'role': 'user'}, {'content': "Answer: C \nExplanation: Mycoplasma:\xa0\n\nThis is a naturally occurring bacteria without cell walls.\xa0\nMycoplasma is classiﬁed as an independent bacterial genus.\xa0\nThey don't require a hypertonic environment for maintenance and are stable in culture medium.", 'role': 'assistant'}]