This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
Von Willebrand factor is produced by 
Select and explain. 
A. Liver, B. Platelets, C. Lungs, D. Spleen
B: Platelets
Answer: B: Platelets 
Explanation: Von Willebrand factor is produced by platelets and endothelial cells Ref: Ganong 25th ed/page 565