This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: vitamins, Subject name: Biochemistry
Both Vitamin K and C are involved in 
Select and explain. 
A. The synthesis of clotting factors, B. Post translational modifications, C. Antioxidant mechanisms, D. The microsomal hydroxylation reactions
B: Post translational modifications
Answer: B: Post translational modifications 
Explanation: Vitamin C plays the role of a coenzyme in the hydroxylation of proline and lysine while procollagen is conveed to collagen (i.e. post-translational modification). The functions of vitamin K are concerned with the blood clotting process. It brings about the posttranslational (after protein biosynthesis in the cell) modification of ceain blood clotting factors ii, vii, ix, x ref Satyanarayana 4th ed page 130, 132