What characterizes memory in adaptive immunity?

• A. It eliminates pathogens during the first exposure only.
• B. It uses innate immune receptors to recognize pathogens.
• C. Upon re-exposure, the response is faster and stronger due to memory B and T cells.
• D. It relies solely on T cells.

Answer: (C)

Memory in adaptive immunity comes from long-lived memory B and memory T cells that persist after the initial exposure. When the same antigen is encountered again, these cells respond rapidly and more vigorously: memory B cells quickly become antibody-secreting plasma cells producing high-affinity antibodies, while memory T cells proliferate and mount swift helper or cytotoxic responses. This produces a faster and stronger secondary immune response compared with the first encounter. The other statements don’t fit because the primary response is what clears pathogens initially, innate immunity relies on non-specific receptors rather than antigen-specific memory, and memory involves both B and T cells, not just T cells.