This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, 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: Stem memory TSCM cells, like naive cells, are CD45RO-, CCR7+, CD45RA+, CD62L+ (L-selectin), CD27+, CD28+ and IL-7Ra+, but they also express large amounts of CD95, IL-2Rb, CXCR3, and LFA-1, and show numerous functional attributes distinctive of memory cells Reff: www.mayoclinic.com', 'role': 'assistant'}]