Plasmin is a proteolytic enzyme; that causes clevase of proteins, mainly derived from an inert plasma precursor known as plasminogen. When clots are formed within blood vessels, they removed by the activation of plasminogen to plasmin which may lead to their removal.
Plasmin is released as a zymogen called plasminogen (inactive form) from the liver into the blood stream (systemic circulation).
I think it is A because the original function of the spinal cord is to complex organization of nerve cells responsible for movement and sensation. It carries signals between the brain and the rest of the body.
