Hematology

Step 1: Initiation of extrinsic pathway.
The extrinsic pathway begins when tissue factor (TF), also called thromboplastin, leaks into the blood from damaged tissues.
So the first step is (C).
Step 2: Activation of clotting factor X.
In the presence of calcium ions (Ca ) and tissue factor, clotting factor X is activated.
So the second step is (D).
Step 3: Formation of active complex.
Activated factor X then combines with factor V in the presence of Ca , forming Prothrombinase complex.
So the third step is (E).
Step 4: Formation of Prothrombinase.
This complex leads to the actual formation of Prothrombinase enzyme.
So the fourth step is (A).
Step 5: Activation of Prothrombinase.
Finally, Prothrombinase is activated and it converts Prothrombin into Thrombin.
So the fifth step is (B).
Step 6: Conclusion.
The correct order is (C) → (D) → (E) → (A) → (B).