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: Medicine
[{'content': "True about Von Willebrand's disease is all c.Ic cpt : \nSelect and explain. \nA. Increased bleeding time, B. Factor VIII c levels are decreased in circulation., C. Increased platelet aggregation in response to Ristocetin, D. APTT is increased", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Answer is C (Increased platelet aggregation in response to Ristocetin) Willebrand disease is characterized by decreased (impaired) platelet aggregation in response to Ristocetin. Deficiency of Factor VIII is characteristic of hemophilia and not VWF disease. VWF however serves as a carrier for factor VIII c and its deficiency therefore leads to decreased availability of factor VIII c at the site of injury. Decaresed level of factor VIII c in the circulation may therefore be explained by a deficiency of vW factor.', 'role': 'assistant'}]