This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nutrition & Digestion, Subject name: Biochemistry
Which Vitamin is required for carboxylation of clotting factors? 
Select and explain. 
A. Vitamin A, B. Vitamin D, C. Vitamin E, D. Vitamin K
D: Vitamin K
Answer: D: Vitamin K 
Explanation: Ans. D. Vitamin K(Ref: Harper 31/e page 529-533)Vitamin K is required for the post-translational carboxylation of glutamic acid (Gamma Carboxylation), which is necessary for calcium binding to g carboxylated proteins.