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
[{'content': 'Vasoconstricting mediator is? \nSelect and explain. \nA. Prostacyclin, B. Thromboxane-A2, C. PG D2, D. Lipoxins', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Thromboxane-A2 Thromboxane-A2 causes vasoconstriction. Other three mediators (given in question) cause vasodilatation.", 'role': 'assistant'}]