This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vitamins and Minerals, Subject name: Biochemistry
All of the following vitamins are anti-oxidants EXCEPT: 
Select and explain. 
A. Beta- carotene, B. Ascorbic acid, C. Vitamin E, D. Vitamin K
D: Vitamin K
Answer: D: Vitamin K 
Explanation: Ans. (d) Vitamin KRef: Harper's Biochemistry, 30th ed. pg. 554-555* Anti-oxidants are vitamin A, C and vitamin E (ACE). Most important of all is vitamin E.* Free-radicals are formed from exposure to sunlight and pollution and also as a byproduct of cell metabolism.* Alcohol, cigarette smoke, stress and even diet also affect the level of free-radical development in the body. Excellent antioxidants include Vitamin A, Vitamin E, Vitamin C, zinc, selenium, ginkgo biloba, grape seed extract, and green tea extract.