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
[{'content': 'On administration of LA in an area of infection, it is not effective because of increase in \nSelect and explain. \nA. Cations, B. Free base, C. Uncharged base, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]