When the molecules in a body move with increased speed, it's possible that the body will change from a
a. liquid to a gas.
b. gas to a liquid.
c. gas to a solid.
d. liquid to a solid.

option a. It is the only valid option because when molecules gain speed they increase their kinetic energy and the processes described in options b, c, and d imply decrease in internal energy, then you can discard them. Regarding, the valid option, a., when the molecules with higher speed will increase their chances to get out of the liquid phase passing to gas state.