This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
Adoptive immunity is by: 
Select and explain. 
A. Infection, B. Injection of antibodies, C. Injection of lymphocytes, D. Immunization
C: Injection of lymphocytes
Answer: C: Injection of lymphocytes 
Explanation: Ans. is 'c' i.e., Injection of lymphocytes(Ref: Jawetz, 27th/e, p. 130)* An extract of immunologically competent T - lymphocytes, known as transfer factor can be used in the treatment of lepromatous leprosy when CMI is low.