ANSWER:
The correct option is A- Electron pairs.
EXPLANATION:
In a chemical bond, the electron pairs are responsible for the formation of a bond. The electrons are gained or lost from atoms so that they can enter into a bond with another atom.
The electrons of an atom may be gained by another atom to maintain the atom in a stable condition. This sharing of electrons is what results in chemical bonds in atoms. Usually, the electrons of the outermost shell of atoms are responsible for chemical bonding.
