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: Surgery
[{'content': 'If a patient is absolutely allergic to LA, the specific drug used in place of it is: \nSelect and explain. \nA. Chlorpheniramine maleate, B. Benzalkonium chloride, C. Diphenhydramine hydrochloride, D. Ketamine hydrochloride', 'role': 'user'}, {'content': 'Answer: C \nExplanation: If the patient is allergic:\n\nTo ester local anesthetics, try an amide local anesthetic.\nTo amide local anesthetics, try an ester local anesthetic.\nTo methylparaben or is allergic to both amide and ester local anesthetics, try a MPF product.\nTo antioxidants or sulfite compounds, review the product ingredients.\n\nSome\xa0 drugs\xa0 like pheniramine,\xa0 promethazine,\xa0 diphenhydramine have\xa0 strong\xa0 while others\xa0 have\xa0 weak\xa0 membrane stabilizing\xa0 property.\nMPF= Methyl paraben Free\xa0\nReference : KDT pharmacology 8th ed page no 180', 'role': 'assistant'}]