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: Surgery
Activity of all local anaesthetic solutions is affected by pH of the tissue or infection except: 
Select and explain. 
A. Propoxycaine, B. Benzocaine, C. Lidocaine, D. None of the above
B: Benzocaine
Answer: B: Benzocaine 
Explanation: As benzocaine has no charge