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: Surgery
Alpha adrenergic agonists are used in combination
with Local anesthetics to 
Select and explain. 
A. increase the rate of liver metabolism of local anesthetic, B. increase the concentration of L.A at receptor site, C. stimulate myocardial contraction, D. increases vascular absorption of L.A
B: increase the concentration of L.A at receptor site
Answer: B: increase the concentration of L.A at receptor site 
Explanation: None