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: Pathology
Memory T cells can be identified by using the following marker: 
Select and explain. 
A. CD45RA, B. CD45RB, C. CD45RC, D. CD45RO
D: CD45RO
Answer: D: CD45RO 
Explanation: CD 45 is called as Leukocyte common antigen (LCA) Location of cell Molecular marker All leucocytes CD45 and CD45RB Medullary thymocytes ('Naive' T- cells) CD45 RA and CD45RC Coical thymocytes (Memory T-cells) CD45RO