This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Marker for B lymphocytes 
Select and explain. 
A. CD34, B. CD33, C. CD19, D. CD20
B: CD33
Answer: B: CD33 
Explanation: Ref immunology by Roitt 6/e p 29; 30; 19 ;9/e p191 CD 19,20,22 are main markers of human B cells .othersB cell markers are CD72 and CD78