Answer: C. The temperature decreases because the average kinetic energy decreases.
Step-by-step explanation:
Kinetic energy is the energy possessed by an object by virtue of its motion.
Average kinetic energy is defined as the average of the kinetic energies of all the particles present in a system. It is given by the equation:
From above, it is visible that kinetic energy is directly related to the temperature of the system. So, if temperature is more, average kinetic energy of the system is more and thus molecules will move faster.
When temperature is decreased, kinetic energy decreases, and the molecules swill move slowly.