Answer: Option (d) is the correct answer.
Step-by-step explanation:
When atoms of a substance are strongly held together due to strong intermolecular forces of attraction then the substance acquires a fixed shape and volume.
Hence, the substance becomes hard in nature.
For example, solids are hard in nature due to the strength of chemical bonds between its atoms which are held by strong intermolecular forces of attraction.
Whereas in liquids, molecules are held by less strong intermolecular forces of attraction. As a result, they do not have fixed shape and volume.
Thus, we can conclude that hardness is related to strength of chemical bonds.