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: Pediatrics
Major source of Von Willebrand factor (vWF) - 
Select and explain. 
A. Erythrocytes, B. Neutrophils, C. Endothelial cells, D. Monocytes
C: Endothelial cells
Answer: C: Endothelial cells 
Explanation: Ans. is `c' i.e., Endothelial cellso Circulating factor VIII has two components.a) Factor VIIIc (Procoagulant protein)o This is the smaller componento-It is synthesized in liver (main source) and kidney.o It is an intrinsic pathway component required for activation of factor X.b) Von willebrand factor (vWF)o This is the larger component.o It is produced by endothelial cells (main source) and megakaryocytes.o It has two major functions ?i) Helps in platelets adhesion by interacting platelet membrane glycoprotein lb-IX.ii) Stabilizes factor VIllc.