19. Which of the following matching among (a) the name of vitamin, (b) the major form of vitamer found in human serum, and (c) the biochemical function of that vitamin is correct? (A) (a) vitamin A; (b) niacin; (c) DNA synthesis (B) (a) vitamin E; (b) α-tocopherol; (c) chain-breaking antioxidant (C) (a) vitamin B1; (b) pyridoxal-5'-phosphate; (c) vision (D) (a) vitamin C; (b) retinol; (c) blood clotting