When gallium is melting in the person’s hand, the changes that occur on a microscopic level are primarily related to the motion and energy of the atoms.
The most appropriate response would be: The gallium atoms will gain kinetic energy.
As the solid gallium melts, the temperature increases, causing the atoms to move faster as they gain kinetic energy. This increased movement allows the atoms to break free from their fixed positions in the solid structure, transitioning into a liquid state.