This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Pharmacology
[{'content': 'Anticoagulant effect of warfarin bus increased by all and the following \nSelect and explain. \nA. Cimetidine, B. Phytonadione, C. Amiodarine, D. Phenyl butazone', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Refer KDT 6/e p 602 Vitamin K1 (phytonadione) is the antidote of warfarin It decreases the effect of oral anticoagulants', 'role': 'assistant'}]