Concept:Fog is an aerosol colloid where a liquid is dispersed in a gas.Explanation:A colloid has a dispersed phase spread through a dispersion medium.In fog, tiny water droplets or ice crystals form the dispersed phase.These liquid droplets are suspended in air, which is the gas medium.This makes fog a liquid aerosol.Thus, liquid particles are dispersed in a gas medium.Answer:A. liquid particles dispersed in a gas medium.