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: Anaesthesia
Drug of choice or differential blockade is 
Select and explain. 
A. Lignocaine, B. Ropivacaine, C. Bupivacaine, D. Dibucaine
B: Ropivacaine
Answer: B: Ropivacaine 
Explanation: Ropivacaine is pure S- isomer of bupivacaine,so less cardiotoxic than bupivacaine. It is drug of choice for differential block.