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
Gamma-carboxylation of glutamic acid in clotting factor II, VII and protein C is dependent on 
Select and explain. 
A. Vitamin K, B. Vitamin C, C. Vitamin A, D. Vitamin E
A: Vitamin K
Answer: A: Vitamin K 
Explanation: Post-translational modification by γ-carboxylation of factor II, VII, IX, IX, and Proteins C and S is vitamin K dependent.