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: Pharmacology
Which of the following is the longest acting LA? 
Select and explain. 
A. Mepivacaine, B. Bupivacaine, C. Dibucaine, D. Chlorprocaine
C: Dibucaine
Answer: C: Dibucaine 
Explanation: Dibucaine: Longest acting LA.
Chlorprocaine: Shortest acting LA.