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
Bleeding time is prolonged in - 
Select and explain. 
A. Von Willebrand's disease, B. Christmas disease, C. Haemophilia, D. Polycythemia
A: Von Willebrand's disease
Answer: A: Von Willebrand's disease 
Explanation: None