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
T-lymphocytes: September 2004 
Select and explain. 
A. 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
B: Are responsible for cell mediated immunity
Answer: B: Are responsible for cell mediated immunity 
Explanation: Ans. B i.e. Are responsible for cell mediated immunity