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: Pathology
In thromboasthenia there is a defect in - 
Select and explain. 
A. Platelet aggregation, B. Platelet adhesion, C. Decreased ADP release, D. Disordered platelet secretion
A: Platelet aggregation
Answer: A: Platelet aggregation 
Explanation: Platelet adhesion

Platelet adhesion refers to the binding of platelets to subendothelial matrix.
Platelet membrane glycoprotein Ib - IX is essential for platelet adhesion to subendothelial matrix.

Platelet aggregation

Platelet aggregation refers to adherence of platelets to one another.
Platelet membrane glycoprotein IIb - IIIa helps in aggregation.

Congenital dysfunction of platelet
1.  Bernard-Soulier syndrome

Defect in platelet adhesion due to inherited deficiency of glycoprotein Ib - IX.

2. Glanzmann's thrombasthenia

Defect in platelet aggregation due to inherited deficiency of glycoprotein IIb - IIIa.