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
Which of the following is most potent vasodilator: 
Select and explain. 
A. Serotonin, B. Bradykinin, C. Histamine, D. Prostaglandin
C: Histamine
Answer: C: Histamine 
Explanation: None