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: Unknown
[{'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: FDA has approved the use of Bosentan for Raynaud’s phenomena', 'role': 'assistant'}]