A 2-Year-Old Boy Has a Bleeding Disorder That Is Clinically

A 2-year-old boy has a bleeding disorder that is clinically indistinguishable from classical hemophilia (hemophilia A) .However, tests for factor VIII activity reveal a normal protein with normal biological properties.Which of the following observations would suggest that the boy has hemophilia B?

A) The plasma level of von Willebrand factor is reduced to 10% of normal.
B) Injected heparin has a paradoxical procoagulant effect.
C) The amino acid hydrolysate of a plasma sample contains an abnormally large quantity of g-carboxyglutamate.
D) The boy's blood clots when mixed with the blood of a patient with hemophilia A, but not when mixed with blood from a patient with hemophilia B.
E) The prothrombin time is normal, but the activated partial thromboplastin time is greatly reduced.