Which of the following postulates of the kinetic-molecular theory best describes Charles's law? Why?

• A. The postulate that best describes Charles's law is "gas particles are always moving quickly and randomly," because this shows that the volume and temperature of gas particles have a linear relationship.
• B. The postulate that best describes Charles's law is "gas particles occupy a much smaller amount of space than the amount of space between particles," because this shows that the pressure and temperature of gas particles have a linear relationship.
• C. The postulate that best describes Charles's law is "gas particle collisions are elastic, whether they are with other particles or the container wall," because this shows that the pressure and temperature of gas particles have a linear relationship.
• D. The postulate that best describes Charles's law is "gas particles' kinetic energy is proportional to the Kelvin temperature," because this shows that the volume and temperature of gas particles have a linear relationship.

Answer: (D)