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: Pathology
Memory T Cells can be identified by using the following marker 
Select and explain. 
A. CD 45 RA, B. CD 45 RB, C. CD 45 RC, D. CD 45 RO
D: CD 45 RO
Answer: D: CD 45 RO 
Explanation: None