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
[{'content': 'Which of the following has lowest Pka value \nSelect and explain. \nA. Lignocaine, B. Chloroprocaine, C. Prilocaine, D. Bupivacaine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Lignocaine has lowest Pkavalue, thus maximum unionised drug at physiological pH. Whereas\xa0chloroprocaine has highest Pka value.', 'role': 'assistant'}]