Final answer:
Plasma is the clear part of blood that contains clotting agents, such as coagulation factors, which work with platelets to form a clot at a wound site.
Step-by-step explanation:
The clear part of whole blood that contains clotting agents is Plasma (A). Blood plasma includes the liquid component of blood and is rich in various substances, including coagulation factors and antibodies. Serum, on the other hand, is the component of plasma without the coagulation factors. Platelets and clotting factors work together to create a clot at a wound site by converting the soluble protein fibrinogen into the insoluble protein fibrin, effectively preventing blood loss and aiding in the healing process.