Answer:
A) the sharing of an electron pair
Explanation:
Covalent bond:
It is formed by the sharing of electron pair between bonded atoms. Â
The atom with larger electronegativity attract the electron pair more towards it self and becomes partial negative while the other atom becomes partial positive.
These compounds are insoluble , hard, having low melting and boiling points and have low conductivity.
For example:
In water the electronegativity of oxygen is 3.44 and hydrogen is 2.2. That's why electron pair attracted more towards oxygen, thus oxygen becomes partial negative and hydrogen becomes partial positive.