Answer: Option (A) is the correct answer.
Explanation:
It is known that when sharing of electrons take place between two combining atoms then the bond formed is known as a covalent bond. In general, a covalent bond is formed between two non-metal atoms.
For example, the compound HCl has a covalent bond between the hydrogen and chlorine atom. As hydrogen atom has 1 valence electron and chlorine atom has 7 valence electrons.
So, in order to attain stability both these atoms will share their valence electrons and hence, a covalent bond is formed.
On the other hand, when an electron is transferred from one atom to another then it tends to form an ionic bond.
For example, the compound NaCl has an ionic bond.
Thus, we can conclude that when atomic orbitals of two nuclei overlap, the mutual attraction between a negatively charged electron pair and the two positively charged nuclei forms a covalent bond.