What are the two types of immunity?

• A. Cellular and humoral immunity
• B. Passive and active immunity
• C. Innate and adaptive
• D. Primary and secondary immunity

Answer: (C)

Immunity is organized into two broad categories: innate (nonspecific) and adaptive (specific). Innate immunity provides immediate defense using barriers like skin and mucous membranes, chemical factors such as stomach acid, and cellular players like phagocytes and natural killer cells, plus the complement system and inflammation. It responds the same way to many pathogens and doesn’t memory-build or tailor its attack to a specific invader.

Adaptive immunity, on the other hand, is activated after exposure to a particular pathogen. It uses T cells and B cells to target that pathogen specifically, producing antibodies and generating memory so future encounters are faster and stronger. This division captures the fundamentally different ways the body defends itself: a rapid, general first line and a targeted, learned response that improves with experience.

The other options describe components or aspects of the immune response rather than the broad categories. Cellular and humoral immunity are the two arms of the adaptive system; passive and active immunity refer to how immunity is acquired; primary and secondary immunity describe responses upon first versus subsequent exposures.