Define immunity.

• A. The process of producing antibodies only
• B. The ability to resist infection and disease
• C. A state of complete invulnerability to all pathogens
• D. A temporary increase in white blood cells during infection

Answer: (B)

Immunity is the body's ability to resist infection and disease. It involves both defenses you’re born with (like skin barriers, inflammation, and phagocytes) and those that develop with exposure (antibodies and T cells that specifically target pathogens). Because of this, immunity isn’t limited to making antibodies; a robust immune system uses multiple layers to recognize, neutralize, and remember invaders. It also isn’t a guarantee of invulnerability to all pathogens—new or overwhelming infections can still occur. A temporary rise in white blood cells during infection is a sign of the immune response, not immunity itself.