The final step in the formation of a blood clot is:

This is because lymph enters the lymph nodes from the collecting ducts, where it is filtered and monitored by immune cells.
From the lymph nodes, lymph travels through larger vessels called lymphatic trunks, which eventually drain into the bloodstream.
Choice A is wrong because veins are blood vessels that carry blood back to the heart, not lymph.
Plasma is the liquid part of blood that contains proteins and other substances.
Choice B is wrong because capillaries are the smallest blood vessels that exchange materials between blood and tissues, not lymph.
Blood supply is the delivery of blood to organs and tissues.
Choice D is wrong because arteries are blood vessels that carry blood away from the heart, not lymph.
Serum is the liquid part of blood that remains after clotting.

The conversion of fibrinogen to fibrin by thrombin is the final step in the formation of a blood clot.
Fibrin is a protein that forms a net-like structure that traps platelets and other blood cells, making the clot stronger and more durable.
Choice A is wrong because the formation of a prothrombin activator is the first step in the formation of a blood clot.
A prothrombin activator is a complex of enzymes that converts prothrombin to thrombin.
Choice B is wrong because the conversion of prothrombin to thrombin by the prothrombin activator is the second step in the formation of a blood clot.
Thrombin is an enzyme that converts fibrinogen to fibrin.
Choice D is wrong because tissue damage is not a step in the formation of a blood clot, but a trigger for the clotting process.
When blood vessels are injured, they release substances that activate platelets and clotting factors.