# Clotting factor common to extrinsic and intrinsic pathway is:

# Clotting factor common to extrinsic and intrinsic pathway is:
A. Factor II
B. Factor III
C. Factor V
D. Factor VII

The correct answer is C. Factor V.

Prothrombin activator that is formed in intrinsic and extrinsic pathways converts prothrombin

into thrombin in the presence of calcium (factor IV). 

Once formed thrombin initiates the formation of more thrombin molecules. The initially formed thrombin activates Factor V. Factor V in turn accelerates formation of both extrinsic and intrinsic prothrombin activator, which converts prothrombin into thrombin. This effect of thrombin is called positive feedback effect.