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': 'Memory T cells can be identified by using the following marker - \nSelect and explain. \nA. CD45 RA, B. CD45 RB, C. CD45 RC, D. CD45 RO', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]