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
Active immunity is not acquired by:(1994) 
Select and explain. 
A. Infection, B. Vaccination, C. Immunoglobulin transfer, D. Sub clinical infection
C: Immunoglobulin transfer
Answer: C: Immunoglobulin transfer 
Explanation: Ans: c (Immunoglobulin transfer)Ref: Ananthanarayan Micro, 7lhed, p. 76 & 6th ed, p. 73