Which type of immunisation is performed by injecting preformed antibo…

The correct answer is Option (2) → Passive immunisation

Acquired immunity can be gained in two ways. When the body meets an antigen and makes its own antibodies, the immunity is active. When ready-made antibodies are given to the body, the immunity is passive. Passive immunity works at once, so it is used where a quick response is needed.

Option (1) Active immunisation — Incorrect. In active immunisation the body is given antigens, as in a vaccine, and it makes the antibodies itself. This response is slow, and no preformed antibodies are injected.

Option (2) Passive immunisation — Correct. Injecting preformed antibodies gives passive immunisation. For tetanus and snakebite, antibodies or antitoxin are injected directly because the body has no time to make its own.

Option (3) Natural immunisation — Incorrect. The book does not use this term. A natural infection, in which microbes enter the body during an illness, makes the body produce its own antibodies, so it leads to active immunity.

Option (4) Innate immunisation — Incorrect. Innate immunity is the non-specific defence present at birth, made up of physical, physiological, cellular and cytokine barriers. It is inborn and does not depend on antibodies, so it cannot be given by an injection.

NCERT Extract:
Active and Passive Immunity – “When a host is exposed to antigens, which may be in the form of living or dead microbes or other proteins, antibodies are produced in the host body. This type of immunity is called active immunity. Active immunity is slow and takes time to give its full effective response. Injecting the microbes deliberately during immunisation or infectious organisms gaining access into body during natural infection induce active immunity. When ready-made antibodies are directly given to protect the body against foreign agents, it is called passive immunity.”
Vaccination and Immunisation – “… If a person is infected with some deadly microbes to which quick immune response is required as in tetanus, we need to directly inject the preformed antibodies, or antitoxin (a preparation containing antibodies to the toxin). Even in cases of snakebites, the injection which is given to the patients, contain preformed antibodies against the snake venom. This type of immunisation is called passive immunisation.”