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
Which of the following fat soluble vitamin has been  identified to function as a coenzyme? 
Select and explain. 
A. Vitamin A, B. Vitamin K, C. Vitamin E, D. Vitamin D
B: Vitamin K
Answer: B: Vitamin K 
Explanation: Most of the water soluble vitamins exert the functions through their respective coenzymes while only one fat soluble vitamin (K) has been identified to function as a coenzyme.
Reference: Satyanarayana- Biochemistry, 3rd edition, pg-117