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
Drug Not used in pulmonary hypertension 
Select and explain. 
A. Calcium channel blocker, B. Endothelin receptor antagonist, C. Alpha blocker, D. Prostacyclin
C: Alpha blocker
Answer: C: Alpha blocker 
Explanation: None