1. The problem asks to identify a colloidal system where the dispersing medium is a gas and the dispersed phase is solid. 2. In colloid chemistry, the dispersing medium is the substance in which particles are dispersed, and the dispersed phase is the substance of the particles. 3. The options are: - A: Buih (foam) - gas dispersed in liquid - B: Aerosol cair (liquid aerosol) - liquid dispersed in gas - C: Asap (smoke) - solid dispersed in gas - D: Debu (dust) - solid dispersed in gas - E: Emulsi (emulsion) - liquid dispersed in liquid 4. Since the medium is gas and the dispersed phase is solid, the correct examples are "asap" (smoke) and "debu" (dust). 5. Among the options, "asap" (smoke) is a classic example of solid particles dispersed in gas. 6. Therefore, the correct answer is C: Asap.