This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood: Hemostasis and Blood Coagulation, Subject name: Physiology
Platelate aggregation is caused by all, except - 
Select and explain. 
A. Thromboxane A2, B. Serotonin, C. Prostacyclin (PGI2), D. Thrombin
C: Prostacyclin (PGI2)
Answer: C: Prostacyclin (PGI2) 
Explanation: Ans. is 'C' i.e.. Prostacyclin (PGI,) o Factors promoting platelet aggregation : ADP, TXA2 epinephrine, serotonin, vWF, fibrinogen, collagen, immune complex, thrombin, thrombospondin. a Factors inhibiting platelet aggregation : PGI2, NO, endothelin, bradykinin.