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: Pharmacology
[{'content': 'Cardiac or central nervous system toxicity may result when standard lignocaine doses are administered to patients with circulatory failure. This may be due to the following reason : \nSelect and explain. \nA. Lignocaine concentration is initially higher in relatively well perfused tissues such as brain and heart., B. Histamine receptors in brain and heart get suddenly activated in circulatory failure, C. There is a sudden outburst of release of adrenaline, noradrenaline and dopamine in brain and heart, D. Lignocaine is converted to a toxic metabolite due to its longer stay in the liver.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]