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
Bosentan is a/an : 
Select and explain. 
A. Serotonin uptake inhibitor, B. Endothelin receptor antagonist, C. Leukotriene modifier, D. Phosphodiestease inhibitor
B: Endothelin receptor antagonist
Answer: B: Endothelin receptor antagonist 
Explanation: None