Final answer:
Plasmin, an enzyme involved in the process of fibrinolysis, digests fibrinogen, a soluble protein that is converted into insoluble fibrin. This helps to dissolve blood clots and restore normal blood flow.
Step-by-step explanation:
Plasmin, an enzyme involved in the process of fibrinolysis, is known to degrade various substances. In addition to Factors Va, VIIIa, and GPIb, plasmin is also known to digest fibrinogen, which is a soluble protein that is converted into insoluble fibrin during the clotting process. Therefore, the correct answer is A) Fibrinogen. Plasmin breaks down fibrinogen into fibrin strands, which helps to dissolve blood clots and restore normal blood flow.