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
Which of the following is not used in the treatment of pulmonary hypertension ? 
Select and explain. 
A. Calcium channel blockers, B. Alpha blockers, C. Prostacyclins, D. Endothelin receptor antagonists
B: Alpha blockers
Answer: B: Alpha blockers 
Explanation: None