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
All of the following are watersoluble radical trapping antioxidants except? 
Select and explain. 
A. Ascorbate, B. Carotenes, C. uric acid, D. Polyphenols
B: Carotenes
Answer: B: Carotenes 
Explanation: Ascorbate, uric acid, and a variety of polyphenols derived from plant foods act as water-soluble radical trapping antioxidants. Ubiquinone and carotenes similarly act as lipid-soluble radical-trapping antioxidants in membranes and plasma lipoproteins. Reference: Harpers illustrated biochemistry 30th edition