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': 'All of the following drugs can prolong bleeding except \nSelect and explain. \nA. Cephalosporins, B. Multiple vitamin K tablets, C. Methylxanthines, D. Anti depressants', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Vitamin K activates clotting factors 2,7, 9 & 10 and decreases chances of bleeding.', 'role': 'assistant'}]