Explanation:
Blood coagulation is initiated by the thromboplastin.
It is also called a tissue factor.
They help in the conversion of prothrombin to thrombin.
With the help of calcium ions and other clotting factors, they convert prothrombin to thrombin.
They are released by blood platelets at the point of injury.
Final answer:
The correct answer is thromboplastin, i.e option (A).
