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: Pharmacology
[{'content': 'Which of the following actions are performed by prostacyclin PGI2 : \nSelect and explain. \nA. Vasodilation and platelet aggregation, B. Vasodilation and inhibition of platelet aggregation, C. Vasoconstriction and platelet aggregation, D. Vasoconstriction and inhibition of platelet aggregation', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]