Gases exert pressure due to which of the following factors?

Gases exert pressure primarily due to particle motion. In a gas, molecules are in constant random motion, colliding with each other and with the walls of the container. These collisions create pressure, which is measured as the force exerted per unit area. The kinetic theory of gases emphasizes the significant role of this motion: the faster the particles move, the more frequent and forceful their collisions with the container walls, resulting in higher pressure.

While temperature can influence particle motion (as increasing temperature tends to increase the kinetic energy of the particles), it is the motion itself that is the direct cause of pressure. The size and mass of the particles can affect properties like the density of the gas or the speed of the molecules, but they are not direct factors in the exertion of pressure in the same fundamental way that particle motion is.