Which statement is true about protective/adaptive immunity?

The statement about protective/adaptive immunity that is true is that it can take time to develop. Adaptive immunity is characterized by its specificity and memory. When the body encounters a pathogen for the first time, the immune system needs time to recognize the specific antigens presented by the pathogen and to generate a tailored immune response. This involves the activation of B cells to produce antibodies and T cells to kill infected cells or help other immune responses. The process typically takes several days to weeks following initial exposure.

After the initial response, the immune system retains a memory of the pathogen, allowing for a quicker and more effective response if the same pathogen is encountered again in the future. This is the basis for immunological memory.

In contrast, immediate responses to an infection are typically mediated by innate immunity, which acts quickly but lacks the specific targeting and long-term memory of adaptive immunity. While adaptive immunity is effective against a wide range of microorganisms, it is not universally effective against all of them, especially if those microorganisms have evasion strategies. Additionally, adaptive immunity does require prior exposure to a pathogen in order to develop the specific antibodies and memory cells that will respond effectively upon subsequent exposures.