This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bleeding disorder, Subject name: Pathology
[{'content': 'Patient with hemophilia A have bleeding disorder because of: \nSelect and explain. \nA. Lack of platelet aggregation, B. Lack of reaction accelerator during activation of factor X in coagulation cascade, C. Neutralization of antithrombin III, D. Release of Thromboxane A2', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Hemophilia A - X- linked disorder -90% cases- deficiency of factor 8 -10% cases - functional defect of factor 8 -Intrinsic Pathway affected -Factor VIIIa complex is the most impoant activator of factor X required for conversion of prothrombin to thrombin. -In symptomatic cases there is a tendency toward easy bruising and massive hemorrhage after trauma or operative procedures', 'role': 'assistant'}]