Pressure of a gas is due to

As per the Kinetic Theory of Gases- The gaseous particles are in constant state of motion randomly in all directions and in straight line. Due to the motion, there is collision of the particles against the walls of the container. This results in the pressure development and is proportional to the number of gas molecules colliding per unit area in unit time on the wall of the container. Thus, the correct option is (d) the collision of gas molecules against the walls of the container