Sol: A colloidal system where a solid is dispersed in a liquid. Examples: Paint, ink, blood, mud. From List-II, Paint (III) is a solid dispersed in a liquid. So, A - III. Foam: A colloidal system where a gas is dispersed in a liquid. Examples: Whipped cream, soap lather, shaving cream. From List-II, Whipped cream (II) is gas (air) dispersed in cream (liquid). So, B - II. Gel: A colloidal system where a liquid is dispersed in a solid. Gels are typically semi-solid. Examples: Jelly, cheese, butter, gelatin. From List-II, Butter (IV) is primarily water (liquid) dispersed in solid fat. So, C - IV. Aerosol: A colloidal system where a solid or liquid is dispersed in a gas. Examples: Fog, mist, cloud (liquid in gas); smoke (solid in gas). From List-II, Cloud (I) is fine droplets of water (liquid) dispersed in air (gas). So, D - I. Combining these matches: A - III B - II C - IV D−I