Which One of the Following Is Not an Assumption Made

Which one of the following is not an assumption made in the kinetic molecular theory of gases?

A) The size of a molecule is negligible.
B) Gas molecules move constantly and randomly throughout the space they occupy.
C) The average kinetic energy of a gas molecule is directly proportional to the absolute temperature of the gas.
D) Collisions of gas molecules with each other and with the walls of the container are elastic.
E) Gas molecules attract and repel each other.