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
Which of the following is not an ester – 
Select and explain. 
A. Amethocaine, B. Benzocaine, C. Procaine, D. Bupivacaine
D: Bupivacaine
Answer: D: Bupivacaine 
Explanation: Bupivacaine is an amide.