What type of immunity is acquired by receiving antitoxin or antiserum containing antibodies?

Passive acquired immunity is characterized by the transfer of antibodies from one individual to another, rather than the recipient's immune system producing these antibodies autonomously. This type of immunity occurs when a person receives antitoxin or antiserum, which contains pre-formed antibodies from an external source, usually derived from another individual's immune response.

In the context of the question, when someone receives antitoxin or antiserum, they are gaining immediate protection against a specific toxin or pathogen without having to mount their own immune response. This is especially useful in situations where immediate immunity is needed, such as in the case of certain venomous bites or infections where the individual has not yet had the opportunity to develop their own antibodies.

The other options, such as active natural immunity, involve the immune system's own response to an infection, while artificially acquired immunity refers to the deliberate introduction of antigens via vaccines, leading to the production of antibodies. Innate immunity, on the other hand, refers to the natural defense mechanisms that are present from birth and do not rely on exposure to pathogens. Thus, passive acquired immunity via received antibodies is correctly identified as the situation described in the question.