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: Pathology
The following is true of Endothelins - 
Select and explain. 
A. Secreted by endothelium, B. Most potent vasoconstrictor, C. Both, D. None
A: Secreted by endothelium
Answer: A: Secreted by endothelium 
Explanation: None