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: Biochemistry
The vitamin used for post-translational modification of glutamic acid to y-Carboxy-glutamate is 
Select and explain. 
A. Vitamin D, B. Vitamin E, C. Vitamin A, D. Vitamin K
D: Vitamin K
Answer: D: Vitamin K 
Explanation: D i.e. Vitamin K