Answer: Option (a) is the correct answer.
Step-by-step explanation:
A bond formed by sharing of electrons is known as a covalent bond. Whereas a bond formed by transfer of electrons is known as an ionic bond.
For example, hydrogen has 1 electron in its valence shell and oxygen needs 2 electrons to completely fill its orbital. Therefore, an oxygen atom combines with two hydrogen atoms by sharing of electrons.
Thus, we can conclude that the statement an oxygen atom shares an electron pair with each H atom, best describes the bonding in a water molecule.