This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
Synthesis of clotting factors needs which vitamin 
Select and explain. 
A. A, B. K, C. D, D. E
B: K
Answer: B: K 
Explanation: K group Catalyze g carboxylation of glutamic acid residues on various proteins concerned with blood clottingRef: Ganong's Review of Medical Physiology Twenty-Third Edition Page No:466