The factor which does not affect the rate of alveolar diffusion is
Solubility of gases
Thickness of the membranes
Reactivity of the gases
The correct option is D Reactivity of the gases
Alveoli are the primary sites of exchange of gases such as oxygen and carbon dioxide by simple diffusion mainly based on pressure/concentration gradient.
The solubility of gasses, as well as the thickness of membranes involved in diffusion, are also some important factors, that can affect the rate of diffusion. Reactivity of gases does not affect the rate of alveolar diffusion as oxygen and carbon dioxide do not react in the alveoli.