This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'Vitamin k associated clotting factors are \nSelect and explain. \nA. 9,10, B. 1,5, C. 7,8, D. 1,81', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ref Robbins 8/e 118-119 ; 9/e p 119 Physiologic Effects of Vitamin K Vitamin K serves as an essential cofactor for a carboxylase that catalyzes carboxylation of glutamic acid residues on vitamin K-dependent proteins. The key vitamin K-dependent proteins include: Coagulationproteins: factors II (prothrombin), VII, IX and X.', 'role': 'assistant'}]