Ferric chloride on rubbing to a bleeding wound causes

• Coagulation is a complex process by which blood forms solid clots. It is an important part of hemostasis whereby a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop bleeding and begin repair of the damaged vessel. As we know blood is a colloidal solution its coagulation can be understood by Hardy-Schulz's law which states that the higher is the charge on cation, the higher will be its efficiency to coagulate the colloidal solution. So according to Hardy-Schulz's law: Ferric chloride is used to stop bleeding in cuts because ${\text{Fe}}^{+3}$ coagulates blood which is negatively charged sol. As we know blood is a colloidal sol. On rubbing the injured part with ${\mathrm{Fe}}^{+3}$ then coagulation of blood takes place. Hence, the main reason is coagulation, which stops bleeding.

Hence, the correct answer is option A) coagulation.