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
Which of the following is a pan-T lymphocyte marker - 
Select and explain. 
A. CD2, B. CD3, C. CD19, D. CD25
B: CD3
Answer: B: CD3 
Explanation: Ans. is 'b' i.e., CD 3 The most clearcut differentiation between T and B cells is by their surface markers, for example, by Demonstration of CD3 of T cells and 1g on B cells.