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': 'True statement regarding lithium toxicity is: \nSelect and explain. \nA. Increased by increased serum sodium levels, B. Increased by decreased serum sodium levels, C. Increased in acute tubular necrosis, D. Appears when the serrum levels become triple the dose of therapeutic levels', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]