Which of the Following Can Explain the Increase in Pressure

Which of the following can explain the increase in pressure that results from decreasing the volume of a fixed amount of gas at a fixed temperature?

A) The gas molecules move faster and therefore hit the walls of the container with more force.
B) The gas molecules have a shorter path between the walls of the container and therefore collide with the walls more frequently.
C) The gas molecules increase in their apparent mass therefore exerting more force when they strike the walls of the container.
D) The gas molecules collide less with each other therefore having more force to exert on the walls of the container.
E) None of these.