The correct option is A gases, solids
∙ Diffusion is the net movement of particles from an area of high concentration to an area of low concentration.
It depends on the space and force of attraction between the particles.
∙ Gases have the largest interparticle space and least intermolecular forces. Due to these properties, the particles move rapidly, hence, the rate of diffusion is higher in gases.
∙ Solids have the least interparticle space and the strongest intermolecular forces. Due to these properties, the particles move slowly.
Hence, the rate of diffusion is the highest in gases and the lowest in solids.