To solve this problem, we need to understand the nature of fog as a colloidal solution.$\\$A colloidal solution is a mixture where one substance is dispersed evenly throughout another.$\\$The dispersed phase consists of small particles that do not settle out.$\\$In the case of fog, it is a type of colloid where liquid droplets are dispersed in a gas.$\\$Specifically, fog consists of tiny water droplets suspended in air.$\\$Let's analyze the options:$\\$• Option 1: Liquid in gas.$\\$• Option 2: Gas in liquid.$\\$• Option 3: Solid in gas.$\\$• Option 4: Gas in gas.$\\$Since fog is made up of liquid water droplets dispersed in the gaseous air,$\\$the correct description of fog as a colloidal solution is "liquid in gas."$\\$Therefore, the correct option is Option 1.