Fog is a colloidal solution of

A colloidal solution is identified by the physical states of the dispersed phase and the dispersion medium.
When the dispersion medium is a gas, the colloid is called an aerosol.

Fog, mist and clouds all have minute droplets of water (liquid) uniformly dispersed throughout air (gas). Hence they belong to the class of aerosols.

Therefore, in fog: dispersed phase = tiny liquid water droplets, dispersion medium = air (gas).

The description that matches this situation is “liquid particles dispersed in gas”.

Option C which is: liquid particles dispersed in gas