This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunomodulators, Subject name: Pharmacology
[{'content': 'Bosentan is \nSelect and explain. \nA. Endothelin receptor blocker, B. ACEI, C. IIb/IIIa receptor blocker, D. None of the above', 'role': 'user'}, {'content': "Answer: A \nExplanation: It is a dual endothelial receptor antagonist. FDA has approved the use of Bosentan for Raynaud's phenomenan, pulmonary aery hypeension. Ref: HL Sharma 3rd ed,Vasoactive peptides", 'role': 'assistant'}]