What is the differences between simple and facilitated diffusion

In terms of their effect on the rate of diffusion, which of the following is the odd one out? a) decreasing the surface area of the membrane b) decreasing membrane permeability c) decreasing lipid solubility of the diffusing molecule d) decreasing the concentration gradient of the diffusing molecule e) decreasing the thickness of the membrane

Name three factors that affect the rate facilitated diffusion across a membrane.