Which statement best differentiates innate immunity from adaptive immunity?

• A. Innate immunity requires prior exposure to a pathogen.
• B. Innate immunity depends upon normally present body functions.
• C. Innate immunity develops later than adaptive immunity.
• D. Innate immunity is more specific than adaptive immunity.

Answer: (B)

Innate immunity relies on pre-existing, normally present body defenses that act immediately and in a non-specific way. These defenses include physical barriers like skin and mucous membranes, chemical barriers such as acidic environments and enzymes, and innate immune cells like neutrophils and macrophages that respond without prior exposure to a pathogen. Because these elements are always there and ready, innate immunity does not require previous encounters with an invader. In contrast, adaptive immunity builds its defenses after exposure, with highly specific responses and memory, which takes time to develop. So describing innate immunity as depending on normally present body functions best captures its essence. The idea that it requires prior exposure is more characteristic of adaptive immunity, the notion that it develops later contradicts its immediate action, and the belief that it is more specific contradicts its non-specific nature.