Final answer:
Passive immunity occurs when an individual receives antibodies from another source, providing immediate but temporary protection without inducing long-term immunological memory. It can be obtained naturally through mother-to-infant transfer or artificially by injecting specific antibodies, as in the case of treatment for a rabid dog bite. The correct option is C.
Step-by-step explanation:
Passive immunity is when an animal receives antibodies that were produced by another animal. This can occur naturally, as when antibodies are passed from the mother to the fetus through the placenta, or through breast milk. Alternatively, it can occur artificially, such as when a person is given injections of antibodies to combat specific infections like rabies.
Unlike active immunity, which is the production of antibodies by the host's own immune system in response to an antigen through infection or vaccination, passive immunity provides immediate protection and does not result in long-term immunological memory. However, the downside of passive immunity is that it lasts only as long as the transferred antibodies remain in the bloodstream, which is usually a few days to a few months.
In the case of a patient bitten by a rabid dog, receiving an injection of specific antibodies is an example of artificial passive immunity because these antibodies are administered from an outside source and provide immediate protection.