Pathology Cells and Tissues of Immune System 6bb1b68f CD marker for cytotoxic T-cells- A CD 4 B CD 8 C CD 21 D CD 45 High-Yield Explanation Ans. is 'b' i.e., CD 8 o Helper T-cells -CD4 positive.o Cytotoxic T-cells and suppressor T-cells - CD 8 positive.