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
Which one of the following  bacteria is  cell  wall  deficient? 
Select and explain. 
A. Escherichia  coli, B. Salmonella  typhi, C. Mycoplasma, D. Treponema pallidum
C: Mycoplasma
Answer: C: Mycoplasma 
Explanation: Mycoplasma: 

This is a naturally occurring bacteria without cell walls. 
Mycoplasma is classiﬁed as an independent bacterial genus. 
They don't require a hypertonic environment for maintenance and are stable in culture medium.