Active immunity is best described as:

Active immunity is best described as:

• A. The body's own production of antibodies after exposure or vaccination
• B. Immunity acquired without exposure to antigen
• C. Transfer of antibodies from another person
• D. Protection that wanes quickly

Answer: (A)

Active immunity is the body's own production of antigen-specific antibodies and memory cells after encountering an antigen, such as a pathogen or a vaccine. When the immune system meets the antigen, B cells become antibody-secreting plasma cells and memory B and T cells are generated, establishing a durable defense. This memory enables a faster and stronger response upon re-exposure to the same antigen, providing long-lasting protection. Immunity acquired without exposure to antigen describes passive or innate immunity, which does not involve the body making its own antibodies or memory and is typically shorter-lived. The idea of protection that wanes quickly also doesn’t fit active immunity, which is designed to be long-lasting and can be reinforced by boosters.

Active immunity is the body's own production of antigen-specific antibodies and memory cells after encountering an antigen, such as a pathogen or a vaccine. When the immune system meets the antigen, B cells become antibody-secreting plasma cells and memory B and T cells are generated, establishing a durable defense. This memory enables a faster and stronger response upon re-exposure to the same antigen, providing long-lasting protection. Immunity acquired without exposure to antigen describes passive or innate immunity, which does not involve the body making its own antibodies or memory and is typically shorter-lived. The idea of protection that wanes quickly also doesn’t fit active immunity, which is designed to be long-lasting and can be reinforced by boosters.