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
Transfer factor is an example of 
Select and explain. 
A. Innate immunity, B. Adoptive immunity, C. Natural active immunity, D. Artificial active immunity
B: Adoptive immunity
Answer: B: Adoptive immunity 
Explanation: Adoptive immunity occurs following injection of immunologically competent T-Lymphocytes known as transfer factor.