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
Vasoconstricting mediator is? 
Select and explain. 
A. Prostacyclin, B. Thromboxane-A2, C. PG D2, D. Lipoxins
B: Thromboxane-A2
Answer: B: Thromboxane-A2 
Explanation: Ans. is 'b' i.e., Thromboxane-A2 Thromboxane-A2 causes vasoconstriction. Other three mediators (given in question) cause vasodilatation.