What are the two functioning parts of the immune system?

• A. Innate and adaptive immunity
• B. Humoral and cellular immunity
• C. Nonspecific and specific immune function
• D. Primary and secondary

Answer: (C)

Two main functioning parts of the immune system are innate and adaptive immunity. The innate system provides quick, general defense right away, using barriers like skin and mucous membranes, plus cells such as neutrophils and macrophages that respond the same way to many pathogens. It doesn’t “remember” past encounters. The adaptive system comes in a bit later but is highly specific; it learns to recognize particular antigens and uses B cells to make antibodies (humoral response) and T cells for targeted, cell-mediated defense. It also forms memory so future exposures are fought off more efficiently. The other descriptions describe parts within the adaptive system or different ways to categorize immune function, but they don’t represent the two broad arms that define how the immune system organizes its response.