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 is always present in bacteria ? \nSelect and explain. \nA. Cell wall, B. Cytoplasmic membrane, C. Mitochondria, D. Nucleoli', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. b. Cytoplasmic membrane', 'role': 'assistant'}]