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
[{'content': 'Active immunity is not acquired by - \nSelect and explain. \nA. Infection, B. Vaccination, C. Immunoglobulin transfer, D. Sub-clinical infection', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Active immunity is the resistance developed by an individual as a result of antigenic stimulus. Naturally acquired active immunity occurs when a person is exposed to a live pathogen, (clinical & subclinical) and develops a primary immune response, which leads to immunological memory. Aificially acquired active immunity can be induced by a vaccine, a substance that contains antigen. A vaccine stimulates a primary response against the antigen without causing symptoms of the disease. Ref: Ananthanarayan & Panikers textbook of microbiology 9th edition pg.no. : 81-84', 'role': 'assistant'}]