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': 'Vitamin K is a cofactor in \nSelect and explain. \nA. Carboxylation, B. Hydroxylation, C. Deaminatiom, D. Hydrolysis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Refer Katzung 10/e p 549 Vitamin K is involved in activition if various clotting factors as well as anticlotting clotting proteins It carries out the final step in activation of these ors I. E, gamma carboxylation of glutamate residues in these factors', 'role': 'assistant'}]