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: Microbiology
[{'content': 'T-lymphocytes: September 2004 \nSelect and explain. \nA. Circulate in the blood in small numbers than B lymphocytes, B. Are responsible for cell mediated immunity, C. Are smaller than B lymphocytes, D. Can become transformed into K cells', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B i.e. Are responsible for cell mediated immunity', 'role': 'assistant'}]