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: Dental
Concentration of adrenaline in local anaesthetic solution for achieving haemostasis & vasoconstriction at surgical site? 
Select and explain. 
A. 1:20000, B. 1:50000, C. 1:80000, D. 1:100000
B: 1:50000
Answer: B: 1:50000 
Explanation: None