Answer: Option-D : <span>Decrease the velocities of the particles, and decrease the space between the particles.
Explanation: The solid state of matter is composed of particles closely packed with a minimum space between them. This closed packing of particles occur due to strong interatomic or intermolecular interactions between particles. Therefore, solids particles have zero translational and rotational motions and only show vibrational motions. So, decrease in velocity and decrease in space between particles is the right answer for making solids.</span>
