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 cannot be used as a surface local anaesthetic? 
Select and explain. 
A. Procaine, B. Tetracaine, C. Lidocaine, D. Benzocaine
A: Procaine
Answer: A: Procaine 
Explanation: None