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: Unknown
The local anesthetic with the longest duration of action is 
Select and explain. 
A. Procaine, B. Chlorprocaine, C. Lignocaine, D. Dibucaine
D: Dibucaine
Answer: D: Dibucaine 
Explanation: Longest acting, most potent and most toxic local anesthetic is dibucaine.
Chlorprocaine is the shortest acting local anesthetic.