This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood Physiology, Subject name: Physiology
Prothrombin Time (PT) detects deficiency of all the following clotting factors EXCEPT 
Select and explain. 
A. II, B. V, C. VII, D. VIII
D: VIII
Answer: D: VIII 
Explanation: The time required for clotting to occur is called the prothrombin time (PT). Normal PT = 15-20 seconds. Prolonged PT suggests the possibility of deficiency of factors II (prothrombin), V, VII and X. Prothrombin level is low in vitamin K deficiency and various liver and biliary diseases.