Which of the assumptions of the kinetic-molecular theory best explains the observations that a gas can be compressed?

• A

  Gas molecules move at random with no attractive forces between them

• B

  The velocity of gas molecules is proportional to their kelvin temperature

• C

  The amount of space occupied by a gas is much greater than the space occupied by the actual gas molecules

• D

  In collisions with the walls of the container or with other molecules, energy is conserved