What does acquired immunity refer to?

Acquired immunity refers to the immunity that develops as a response to exposure to pathogens or through vaccination. It includes two primary mechanisms: immunity that develops after recovering from an infection, which occurs when the body produces antibodies against specific pathogens, and immunity gained through vaccinations, where a vaccine stimulates the immune system to recognize and combat pathogens without causing the disease.

When a person recovers from an infection, their immune system has already encountered the pathogen and created a memory response, enabling quicker and more effective responses to future infections by the same pathogen. Similarly, vaccines work by introducing antigens into the body, prompting the immune system to produce a protective response, including memory cells that will respond more vigorously if the actual pathogen is encountered later.

Thus, acquired immunity encompasses both the immunity resulting from recovering from an infection and from vaccinations, which is why the correct choice identifies both of these sources as aspects of acquired immunity.