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
Concentration of lignocaine used – a) 2%b) 4%c) 5%d) 10%e) 1% 
Select and explain. 
A. bcde, B. abcd, C. abce, D. abde
C: abce
Answer: C: abce 
Explanation: Lignocaine is used in different concentrations for different regional blocks :- Surface (topical) anesthesia: 4%, Nerve block : 1-2%, Spinal anesthesia : 5%, Epidural : 1-2%, Bier's block : 0.5% and infiltration block : 1-2%.