Answer: Option (C) is the correct answer.
Explanation:
In a solid, molecules are held together by strong intermolecular forces of attraction. As a result, they are unable to move from their initial place but they can vibrate at their mean position.
Hence, in solid substances the molecules have low kinetic energy and they have fixed shape and volume.
In gases, the molecules are held by weak Vander waal forces. Hence, they have high kinetic energy due to which they move rapidly from one place to another leading to more number of collisions.
Hence, gases are able to expand more rapidly as compared to liquids and solids.
Thus, we can conclude that the statement atoms of both are moving, is true about both a solid and a gas.