This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bleeding Disorders, Subject name: Pathology
Extrinsic pathway of clotting factors is measured by? 
Select and explain. 
A. Prothrombin time, B. Activated partial thromboplastin time, C. Bleeding time, D. Clotting time
A: Prothrombin time
Answer: A: Prothrombin time 
Explanation: Ans. (a) Prothrombin timeRef: Robbin's pathology 9th ed. /116-18Prothrombin timeExtrinsic pathwayFactor 5/7Activated partial thromboplastin timeIntrinsic pathwayFactor 8Bleeding timePlatelet function and platelet countPlatelet function and count