The correct option is D All of these
Diffusion is a passive movement of molecules or ions from a region of their higher concentration to lower concentration till a level of equilibrium is reached. There are several factors that affect diffusion like temperature, concentration gradient, size of molecules.
The rate of diffusion increases with increasing temperature.
The molecules with smaller size diffuse faster when compared to larger molecules.
The difference in the concentration of a molecule or ion between two areas is called concentration gradient. If the difference of concentration is high between the two areas, then the substances move faster.