Which type of bond involves the sharing of electron pairs between atoms?

A. Metallic bond: Metallic bonds involve the delocalized sharing of electrons among a lattice of metal atoms, providing conductivity and malleability, but not discrete electron pair sharing between specific atoms.

B. Hydrogen bond: Hydrogen bonds are weak attractions between a hydrogen atom covalently bonded to one electronegative atom and another electronegative atom; they do not involve direct electron pair sharing.

C. Covalent bond: Covalent bonds form when two atoms share one or more pairs of electrons to achieve stable electron configurations, creating strong and specific molecular connections.

D. Ionic bond: Ionic bonds result from the electrostatic attraction between oppositely charged ions following electron transfer, rather than sharing electron pairs.

A. To provide immediate defense against all pathogens: Nonspecific, or innate, immunity acts as the first line of defense by responding rapidly to pathogens. It includes barriers like skin, mucous membranes, and phagocytic cells that act regardless of the pathogen type.

B. To enhance the body's inflammatory response: While nonspecific immunity involves inflammation, enhancing the inflammatory response is a mechanism rather than the primary role. Its main function is broad and immediate defense.

C. To target specific pathogens based on antigens: Targeting specific pathogens is a function of specific (adaptive) immunity, which recognizes antigens and produces tailored responses.

D. To produce memory cells for long-term immunity: Memory cell production is part of adaptive immunity. Nonspecific immunity does not have memory and reacts the same way to repeated exposures.