This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Clotting system, Subject name: Pathology
[{'content': 'Vitamin required for bone formation as well as coagulation cascade is: \nSelect and explain. \nA. A, B. D, C. E, D. K', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Vitamin K is the cofactor for g-carboxylation of glutamate residues of protein to produce g-carboxy glutamate (gla). This process is known as Vitamin K epoxide cycle. Clotting factors contain 4 to 6 g-carboxyglutamate residues:- Eg- II VII IX X Protein C Protein S Protein Z Osteocalcin Transthyretin (Prealbumin)', 'role': 'assistant'}]