This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (Local and Regional Anesthesia), Subject name: Anaesthesia
All are amides EXCEPT: 
Select and explain. 
A. Lignocaine, B. Procaine, C. Prilocaine, D. Etidocaine
B: Procaine
Answer: B: Procaine 
Explanation: ANSWER: (B) ProcaineREF: KDT 4th edition page 161Amide linked LA(Mnemonic = two "I" in the spelling)Ester linked LA(Mnemonic= one "I" in the spelling)Lignocaine (Lidocaine/xylocaine)BupivacaineDibucainePrilocaineRopivacaineCocaineProcaineChlorprocaineTetracaineBenzocaine