Which statement describes innate immunity?

• A. It requires vaccines to be functional.
• B. It is present from birth and acts against a broad range of pathogens.
• C. It is passed from mother to child exclusively.
• D. It develops after exposure to pathogens.

Answer: (B)

Innate immunity is the body's built-in, non-specific defense that is present from birth and provides immediate protection against a wide range of pathogens. It doesn't depend on previous encounters or vaccines; instead, barriers like skin and mucous membranes, along with cells such as neutrophils and macrophages and the complement system, respond quickly to many invaders. That makes the statement describing innate immunity as present from birth and acting against a broad range of pathogens the best fit. In contrast, relying on vaccines points to adaptive immunity, which develops more targeted responses after exposure; maternal transfer of immunity refers to passive antibodies passed from mother to child, which is a separate mechanism from innate defense. Developing after exposure to pathogens is characteristic of adaptive immunity, which learns and remembers specific pathogens for future protection.