Final answer:
Reactive immunity is not one of the three recognized types of immunity; instead, the main types are innate, active, and passive immunity.
Step-by-step explanation:
The type of immunity that is NOT one of the three types is Reactive immunity. The recognized forms of immunity are innate, active, and passive immunity.
Innate immunity is the body's first line of defense against pathogens and is present from birth. It includes physical barriers like skin and mucous membranes, as well as immune system cells that attack foreign substances.
Active immunity is acquired when a person's own immune system generates an immune response to a pathogen. An example of active immunity is when someone recovers from an infection and their body has produced antibodies to fight off a particular pathogen. Vaccinations also provide active immunity, as they train the immune system to recognize and combat specific pathogens without causing the disease.
Passive immunity occurs when a person is given antibodies from another person or animal, rather than producing them through their own immune system. This can happen naturally, as in the case of antibodies a baby receives through the mother's placenta or breast milk, or artificially, such as with the administration of immunoglobulins for certain medical conditions.
Reactive immunity, however, is not a recognized class of immunity in medical literature.