The correct answer is:
C. valence.
Explanation:
The valence or valency of an element is a stratagem of its connecting power with other atoms when it makes chemical compounds or molecules.
A valence electron is an outer shell electron that is connected with an atom, and that can compete in the formation of a chemical bond if the outer shell is not closed; in a single covalent bond, both atoms in the bond provide one valence electron in order to form a shared pair.
