The correct option is B Introduction of antigens deliberately during vaccination
Immunity is the ability of the organism to fight against all the disease-causing pathogens that enter the body.
It is of two types, innate and acquired.
Innate immunity is present since birth and is non-specific.
Acquired immunity is very specific. It develops gradually in an organism.
Acquired immunity is of two types, active immunity and passive immunity.
In active immunity, antibodies are produced by the body against specific antigens (substances capable of generating an immune response). It is slow and takes time to give its full effective response.
When the infectious organisms enter into the body during natural infection, they induce natural active immunity.
Vaccination is a form of artificial active immunity. In vaccination, the disease-causing microbes or components of pathogens (antigens) are deliberately introduced into the body in either killed or inactivated form. This will not result in disease but rather the body starts producing antibodies against that pathogen.
On the other hand, passive immunity involves transfer of antibodies directly to protect the body against foreign agents. The transfer of IgG antibodies from the mother to the foetus is an example of passive immunity. Passive immunity also involves the transfer of antibodies through colostrum to the new-born. Colostrum is the initial milk produced by the mother after the delivery of the child. Colostrum is rich in IgA antibodies.