This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunity, Subject name: Pathology
Which of these is CD marker of cytotoxic cells? 
Select and explain. 
A. CD8, B. CD4, C. CD1a, D. CD1
A: CD8
Answer: A: CD8 
Explanation: Ans. (a) CD8(Ref: Robbins 9th/pg 191; 8th/pg 186)CD8Is a marker for cytotoxic T cellsActs as a co-receptor for TCRBinds to HLA-I to cause cytotoxic effect on virus infected and tumor cells