We can easily move our hand in air because:

Whether or not we can move our hands easily across the specified medium will depend on the distance between the particles. In contrast to liquids and gases, solids have far less space between their particles. The intermolecular attraction is greatest in solids and least in gases. So the movement of hands in the air is easy because in the air the atoms are loosely bound. The space between two molecules in the air is very high. And they easily displace when our hand moves. The force of attraction between the particles is very low when the intermolecular space is very high. The force of attraction between the particles is inversely correlated with the intermolecular spacing of the particles.

Hence, option C is correct.