The state of matter which can be easily compressed is:
gases
Explanation for the correct option: (c) The particles of gases are loosely packed as compared to solids and liquids. The intermolecular space in gases is very large and the intermolecular force of attraction is very weak.
Explanation for the incorrect options: (a) The particles of solid are very closely packed. The intermolecular space in solids is negligible and the intermolecular force of attraction is very strong.
(b) The particles of liquid are not as closely packed as solids, but more closely packed than gases. The intermolecular space is appreciable and the intermolecular force of attraction is less than solids but more than gases.
Hence, option (c) is correct, that is, the state of matter that can be most easily compressed is gas.