A 28 year old female teacher is found to have a prolonged bleeding time and normal platelet count. She had a bleeding of "easy bleeding" with frequent bleeding of the gums, epistaxis, cutaneous bleeding and menorrhagia, further testing revealed a deficiency of Von willebrand factor. Which of the following thrombogenic processes involving platelets is most directly impaired?
Disruption of the endothelium exposes subendothelial Von willebrand factor (VWF) and collagen, which promotes platelet adherence and activation.
Deficiency of Von willebrand factor (VWF) causes


↓ Platelet adhesion (↑ BT)


↓ Intrinsic pathway activity (↑ aPTT)
Adhesion
Aggregation
Formation of fibrinogen bridges
Conformational change with activation of phospholipid surface