During the process of blood coagulation, vitamin K helps in
A. The formation of prothrombin
B. The formation of thromboplastin
C. The conversion of fibrinogen into fibrin
D. The conversation of prothrombin into thrombin

Hint:-Blood coagulation also stops as blood clotting. In this process, blood alters from a fluid to a gel and forms a clot of blood. It stops the loss of blood from an injured blood vessel. It proceeds just immediately after a wound to the blood vessel has injured the endothelium lining of the blood vessel.

Complete Answer:-
Blood clotting mechanism comprises the presence of calcium and other clotting factors. Prothrombinase prompts an enzyme and is referred to as a prothrombin activated in the presence of calcium ions and thrombokinase promotes the conversion of plasma protein prothrombin into enzyme thrombin during blood coagulation. The formation of thrombin enzymes catalysis the transformation of fibrinogen into fibrin. Platelets and fibrin polymerized jointly to create a clot at the site of a wound (the process is known as blood coagulation). Prothrombin is formed in the liver. It serves as a plasma protein. For the formation of prothrombin Vitamin K is crucial because it restores the mechanism by which synthesis of prothrombin occurs.
Thus, the right option is A.

Note:- Deficiency of vitamin K in human infants results in haemorrhagic disease and may cause permanent brain damage or death. Also due to insufficient intake of vitamin K, the density of bones is reduced that may increase the chance of fractures. Because vitamin K plays an important role in the production of a bone protein known as osteocalcin and increases the quality of bone.