Which substance, containing a mucopolysaccharide and found in the liver, plays a role in platelet aggregation?

Explanation

Heparin is a mucopolysaccharide produced in the liver that influences platelet aggregation and acts as an anticoagulant. Plasmin breaks down clots, aspirin inhibits platelet function, and prothrombin is a clotting factor, not a mucopolysaccharide.