This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
All are to access platelet functions except ? 
Select and explain. 
A. Prothrombin time, B. Bleeding time, C. Clot retraction time, D. all
A: Prothrombin time
Answer: A: Prothrombin time 
Explanation: Ans. is 'a' i.e., Prothrombin time