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
It is difficult to obtain local infiltration anesthesia in the presence of inflammation because of 
Select and explain. 
A. a decreased PH, B. increased vascularity, C. oedema, D. pain
A: a decreased PH
Answer: A: a decreased PH 
Explanation: None