The correct option is A collidel
Electrical properties of a colloidal solution are demonstrated by electrophoresis. It is the migration of colloidal particles under the effect of electric field. Both the colloidal particles and the dispersion medium carry electrical charge. Under an influence of electric field, they move in opposite direction. When the experimental conditions are arranged in such a way that only colloidal particles migrate but not the medium, the phenomenon is called electrophoresis.