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: Medicine
[{'content': 'Drug Not used in pulmonary hypertension \nSelect and explain. \nA. Calcium channel blocker, B. Endothelin receptor antagonist, C. Alpha blocker, D. Prostacyclin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]