Which among the following is the last reaction during blood clotting?

An injury or a trauma stimulates the blood platelets and damaged tissues to release certain factors which activate the mechanism of coagulation. This leads to the formation of thrombokinase which converts prothrombin to thrombin. Thrombin converts fibrinogen to fibrin. The clot or coagulum formed mainly of a network of threads called fibrins in which dead and damaged formed elements of blood are trapped.