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
[{'content': 'CD marker for cytotoxic T-cells \nSelect and explain. \nA. CD 4, B. CD 8, C. CD 21, D. CD 45', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., CD 8 Helper T-cells --> CD4 positive. o Cytotoxic T-cells and suppressor T-cells --> CD 8 positive.", 'role': 'assistant'}]