This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Regional anaesthesia, Subject name: Anaesthesia
[{'content': "In Bier's block anaesthetic agent given by which route \nSelect and explain. \nA. Intravenous, B. Peribulbar region, C. Retrobulbar area, D. Dermal", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Biers&;s block is intravenous regional anaesthesia', 'role': 'assistant'}]