Vitamin K is essential for the formation of factor VII, IX, X, and prothrombin. It is synthesized in the intestinal tract by bacteria. Blood coagulation or clotting takes place in 3 essential phases. The first phase is the activation of a prothrombin activator complex. The second phase is the activation of prothrombin. The third stage is clot formation as a result of fibrinogen cleavage by activated thrombin. Thus, its deficiency can result in excessive bleeding.
So, the correct answer is option A.