Which process is associated with an increase in kinetic energy, and what experimental evidence supports this?
a. the transition period during which a solid is changing state into a liquid; its temperature is remaining constant
b. the period during which a solid is not changing state; its temperature is increasing
c. the period during which the gas is not changing state; its temperature is decreasing
d. the transition period during which a liquid is changing to a gas; its temperature is remaining constant