This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
All are B cell marker except- 
Select and explain. 
A. CD-15, B. CD-19, C. CD-21, D. CD-23
A: CD-15
Answer: A: CD-15 
Explanation: Reference :Robbins basic pathology 9th edition pg no 117:Some are the signaling molecules attached to the BCR; another example is CD21 (also known as the type 2 complement receptor, or CR2), which recognizes a complement break- down product that frequently is deposited on microbes and promotes B cell responses to microbial antigens. Inter- estingly, the ubiquitous Epstein-Barr virus has cleverly evolved to use CD21 as a receptor for binding to B cells and infecting them.