Which type of immunity is present from birth and provides immediate, non-specific defense?

• A. Active immunity
• B. Passive immunity
• C. Adoptive immunity
• D. Natural immunity

Answer: (C)

Innate immunity, or natural immunity, is the defense you’re born with. It provides immediate protection and is non-specific, meaning it responds in the same general way to a wide range of pathogens rather than targeting a specific one. This system includes physical barriers like skin and mucous membranes, and internal defenses such as phagocytes (neutrophils and macrophages), natural killer cells, the complement system, and the inflammatory response. Because these defenses are built in and ready to act, they kick in right away without prior exposure.

Active (adaptive) immunity develops after exposure to a pathogen or vaccine and creates specific antibodies with memory for faster responses in the future. Passive immunity involves receiving antibodies from another person or animal and is immediate but temporary and targeted. Adoptive immunity isn’t a standard term for a natural defense.