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': 'Transfer factor is an example of: \nSelect and explain. \nA. Artificial active immunity, B. Natural active immunity, C. Adoptive immunity, D. Artificial passive immunity', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Acquired by injection of immunologically competent T-lymphocytes known as Transfer factor\nUsed for treatment when the CMI is low, e.g. Lepromatous leprosy.', 'role': 'assistant'}]