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': 'The following statements regarding methylxanthines are true except: \nSelect and explain. \nA. It enhances the receptor - mediated actions of adenosine, B. It can enhance water and electrolyte excretion, C. It can relax bronchial smooth muscles, D. Long-term ingestion can produce tolerance and physical dependence', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Methyl xanthines inhibit cyclic nucleotide phosphodiesterases and can antagonize receptor-mediated actions of adenosine.\nLong-term ingestion of methyl xanthines can produce tolerance and\xa0physical dependence.\nIt can relax various smooth muscles including the bronchial muscles.\nIt increases\xa0glomerular ﬁltration rate and increases the excretion of electrolytes and water.', 'role': 'assistant'}]